//
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// FFPageViewController.m
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// FFPage
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//
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// Created by North on 2019/8/5.
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// Copyright © 2019 North. All rights reserved.
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//
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#import "FFPageViewController.h"
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NS_INLINE CGRect frameForPage(FFPageViewController *controller, NSInteger page){
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CGFloat x = controller.scrollDirection != ScrollDirectionVertical?page * CGRectGetWidth(controller.scrollview.frame):0;
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CGFloat y = controller.scrollDirection != ScrollDirectionVertical?0:page * CGRectGetHeight(controller.scrollview.frame);
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return CGRectMake(x, y,CGRectGetWidth(controller.scrollview.frame), CGRectGetHeight(controller.scrollview.frame));
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}
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NS_INLINE NSInteger pageFormOffset(UIScrollView *scrollView){
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CGPoint point = scrollView.contentOffset;
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double scale = scrollView.contentSize.width > CGRectGetWidth(scrollView.bounds)? point.x/CGRectGetWidth(scrollView.bounds):point.y/CGRectGetHeight(scrollView.bounds);
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NSInteger page = roundl(scale); //四舍五入 取出在屏幕中最多显示区域的页码
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return page;
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}
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@interface FFPageViewController ()<UIScrollViewDelegate>
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/**
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缓存
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*/
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@property (strong, nonatomic) NSMapTable * cacheMaps;
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/**
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存储页数的数组
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用于简单实现LRU算法
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*/
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@property (strong, nonatomic) NSMutableArray * pagesArray;
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/**
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用户开始拖拽钱的偏移量
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*/
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@property (assign, nonatomic) CGPoint startOffset;
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/**
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runloop观察者
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*/
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@property CFRunLoopObserverRef observer;
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/**
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计时器 保证runloop不退出
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*/
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@property (retain, nonatomic) NSTimer * timer ;
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@end
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@implementation FFPageViewController
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@synthesize currentPage = _currentPage;
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@synthesize scrollview = _scrollview;
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@synthesize currentController = _currentController;
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- (void)viewDidLoad {
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[super viewDidLoad];
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[self setUpView];
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[self setUpRunloop];
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}
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- (void)setUpView{
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[self.view addSubview:self.scrollview];
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}
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#pragma mark - Runloop
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- (void)setUpRunloop{
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[self removeRunloop];
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if(self.prePages <= 0 && self.maxPages <= 0) return;
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__weak typeof(self) weakself=self;
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CFRunLoopObserverRef observer = CFRunLoopObserverCreateWithHandler
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(kCFAllocatorDefault, kCFRunLoopBeforeWaiting, true,NSIntegerMax - 999, ^(CFRunLoopObserverRef observer, CFRunLoopActivity activity) {
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[weakself preControllers];
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});
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CFRunLoopAddObserver(CFRunLoopGetMain(), observer, kCFRunLoopDefaultMode);
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self.observer = observer;
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NSTimer * timer = [NSTimer timerWithTimeInterval:.1 target:self selector:@selector(timerChanged) userInfo:nil repeats:YES];
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[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
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self.timer = timer;
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}
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- (void)timerChanged{}
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- (void)removeRunloop{
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if(self.timer){
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CFRunLoopRemoveObserver(CFRunLoopGetMain(), self.observer, kCFRunLoopDefaultMode);
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CFRelease(self.observer);
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[self.timer invalidate];
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self.timer = nil;
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}
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}
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- (void)preControllers{
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if (![self isRespondsDelete]) return;
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if(!self.currentController) return;
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NSInteger page = self.currentPage - self.prePages;
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page = MAX(page, 0);
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NSInteger end = MIN([self totalPages], self.currentPage + self.prePages + 1);
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for (NSInteger index = page; index < end; index ++) {
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if(![self.pagesArray containsObject:@(index)]){
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[self addConrolerForPage:@(index)];
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return;
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}
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}
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BOOL maxPageSure = self.maxPages >= self.prePages * 2 + 1;
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maxPageSure = maxPageSure && self.maxPages < self.pagesArray.count;
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//如果缓存数量过多 释放最后一个控制器
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if(maxPageSure){
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[self removeControllerForPage:self.pagesArray.lastObject];
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return;
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}
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}
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#pragma mark - 外部调用
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- (void)reloadData{
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//检查代理
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NSAssert([self isRespondsDelete], @"请实现代理FFPageViewControllerDelegate");
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[self.pagesArray enumerateObjectsUsingBlock:^(NSNumber * page, NSUInteger idx, BOOL * _Nonnull stop) {
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[self removeControllerForPage:page];
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}];
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[self.pagesArray removeAllObjects];
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//如果当前页 超过最大页数 置为0
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if ([self totalPages] < self.currentPage) {
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_currentPage = 0;
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}
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[self updateDisplay];
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}
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- (void)updateTotalCount{
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[self updateContentSize];
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//调整位置
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[self addConrolerForPage:@(_currentPage)];
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//调整滚动量
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self.scrollview.contentOffset = frameForPage(self, self.currentPage).origin;
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}
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- (void)scrollToPage:(NSInteger)page animation:(BOOL)animation{
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_currentPage = page;
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//没有实现代理
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if (![self isRespondsDelete]) return;
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//页码不正确
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if (page < 0 || [self totalPages] <= page ) return;
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//还没调整完位置
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if (!CGRectEqualToRect(self.view.bounds, self.scrollview.frame))return;
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[self.scrollview setContentOffset:frameForPage(self, page).origin animated:animation];
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[self addConrolerForPage:@(page)];
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if(!animation){
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[self updateAppearance:page];
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}
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}
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#pragma mark - 更新控制器/视图
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- (void)updateDisplay{
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//调整 scrollview的contentSize
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[self updateContentSize];
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//没有当前控制器代表没有初始化 设置当前页是默认页
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if(!_currentController) _currentPage = self.defaultPage;
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//调整位置
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[self addConrolerForPage:@(_currentPage)];
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//调整滚动量
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self.scrollview.contentOffset = frameForPage(self, self.currentPage).origin;
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[self updateAppearance:_currentPage];
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}
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/**
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更新滚动区域大小
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*/
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- (void)updateContentSize{
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NSInteger maxPage = [self totalPages] - 1;
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CGRect maxPageFrame = frameForPage(self, maxPage);
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self.scrollview.contentSize = CGSizeMake(CGRectGetMaxX(maxPageFrame), CGRectGetMaxY(maxPageFrame));
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}
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/**
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添加子控制器以及视图
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@param page 页码
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*/
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- (void)addConrolerForPage:(NSNumber *)page{
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NSInteger intPage = [page integerValue];
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//越界 直接返回
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if (intPage < 0 || intPage >= [self totalPages]) return;
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//已经添加
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if ([self.pagesArray containsObject:page]){
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UIViewController *controller = [self.cacheMaps objectForKey:page];
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//可能涉及到调整屏幕旋转 需要调整frame
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controller.view.frame = frameForPage(self, intPage);
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[self.scrollview bringSubviewToFront:controller.view];
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[self.pagesArray removeObject:page];
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[self.pagesArray insertObject:page atIndex:0];
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return;
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}
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UIViewController * controller = [self.delegate pageViewController:self controllerForPage:intPage];
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controller.view.frame = frameForPage(self, intPage);
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[self addChildViewController:controller];
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[self.scrollview addSubview:controller.view];
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[controller didMoveToParentViewController:self];
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[self.cacheMaps setObject:controller forKey:page];
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[self.pagesArray insertObject:page atIndex:0];
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}
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/**
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删除子控制器以及视图 并释放内存
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@param page 页码
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*/
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- (void)removeControllerForPage:(NSNumber *)page{
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if (![self.pagesArray containsObject:page]) return;
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[self.pagesArray removeObject:page];
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UIViewController *controller = [self.cacheMaps objectForKey:page];
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[controller willMoveToParentViewController:nil];
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[controller.view removeFromSuperview];
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[controller removeFromParentViewController];
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controller = nil;
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[self.cacheMaps setObject:controller forKey:page];
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}
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/**
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是否实现代理
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@return YES 代表实现
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*/
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- (BOOL)isRespondsDelete{
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return self.delegate && [self.delegate respondsToSelector:@selector(totalPagesOfpageViewController:)] && [self.delegate respondsToSelector:@selector(pageViewController:controllerForPage:)];
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}
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/**
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获取总页数
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@return 总页数
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*/
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- (NSInteger)totalPages{
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if(![self isRespondsDelete]) return 0;
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return [self.delegate totalPagesOfpageViewController:self];
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}
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- (void)viewDidLayoutSubviews{
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[super viewDidLayoutSubviews];
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if (!CGRectEqualToRect(self.view.bounds, self.scrollview.frame)){
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self.scrollview.frame = self.view.bounds;
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if (![self isRespondsDelete]) return;
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[self updateDisplay];
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}
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}
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#pragma mark - UIScrollViewDelegate
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//用户开始拖拽
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- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
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if (!scrollView.isDecelerating) self.startOffset = scrollView.contentOffset;
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}
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- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
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if(self.delegate && [self.delegate respondsToSelector:@selector(pageViewController:contentOffSetChanged:)]){
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[self.delegate pageViewController:self contentOffSetChanged:scrollView.contentOffset];
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}
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//手指触摸时才允许添加视图 防止滚动距离过大 全部加载到内存中 引起CPU内存暴增
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if (!scrollView.isDragging) return;
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NSInteger page = pageFormOffset(scrollView);
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//添加下一页控制器
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NSInteger nextPage = page;
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if (scrollView.contentOffset.x > self.startOffset.x || scrollView.contentOffset.y > self.startOffset.y) nextPage ++ ;
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else if (scrollView.contentOffset.x < self.startOffset.x || scrollView.contentOffset.y < self.startOffset.y) nextPage --;
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[self addConrolerForPage:@(nextPage)];
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}
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//结束减速 用户触摸滚动结束后调用
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- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
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NSInteger page = pageFormOffset(scrollView);
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[self updateAppearance:page];
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}
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//结束动画 非用户触摸滚动结束后调用
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- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
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NSInteger page = pageFormOffset(scrollView);
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[self updateAppearance:page];
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}
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#pragma mark - 子控制器生命周期
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- (void)updateAppearance:(NSInteger)page{
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UIViewController * controller = [self.cacheMaps objectForKey:@(page)];
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if(controller != _currentController){
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if(_currentController)[_currentController beginAppearanceTransition:NO animated:YES];
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[controller beginAppearanceTransition:YES animated:YES];
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if(_currentController)[_currentController endAppearanceTransition];
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[controller endAppearanceTransition];
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_currentPage = page;
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_currentController = controller;
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if(self.delegate && [self.delegate respondsToSelector:@selector(pageViewController:currentPageChanged:)]){
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[self.delegate pageViewController:self currentPageChanged:_currentPage];
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}
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}
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}
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// 自控制器生命周期不跟随父类
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- (BOOL)shouldAutomaticallyForwardAppearanceMethods{
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return NO;
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}
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#pragma mark - getter 懒加载
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- (UIScrollView *)scrollview{
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if (!_scrollview){
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_scrollview = [UIScrollView new];
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_scrollview.pagingEnabled = YES;
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_scrollview.delegate = self;
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_scrollview.showsVerticalScrollIndicator = NO;
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_scrollview.showsHorizontalScrollIndicator =NO;
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if (@available(iOS 11.0, *)) {
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_scrollview.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
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}
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}
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return _scrollview;
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}
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- (NSMapTable *)cacheMaps{
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if (!_cacheMaps) _cacheMaps = [NSMapTable strongToWeakObjectsMapTable];
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return _cacheMaps;
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}
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- (NSMutableArray *)pagesArray{
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if (!_pagesArray) _pagesArray = @[].mutableCopy;
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return _pagesArray;
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}
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- (NSInteger)currentPage{
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return _currentPage;
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}
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#pragma mark 生命周期
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- (void)viewWillAppear:(BOOL)animated{
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[super viewWillAppear:animated];
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[self.currentController beginAppearanceTransition:YES animated:YES];
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if(!self.timer)[self setUpRunloop];
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}
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- (void)viewDidAppear:(BOOL)animated{
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[super viewDidAppear:animated];
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[self.currentController endAppearanceTransition];
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}
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- (void)viewWillDisappear:(BOOL)animated{
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[super viewWillDisappear:animated];
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[self.currentController beginAppearanceTransition:NO animated:YES];
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[self removeRunloop];
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}
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- (void)viewDidDisappear:(BOOL)animated{
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[super viewDidDisappear:animated];
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[self.currentController endAppearanceTransition];
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}
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@end
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