//// ViewController.m// 無限輪播//// Created by limin on 17/8/23.// Copyright © 2017年 none. All rights reserved.// #import "ViewController.h" @interface ViewController ()<UIScrollViewDelegate>/* 定時器 */@property(nonatomic,strong)NSTimer *rotateTimer;/* */@property(nonatomic,strong)UIPageControl *myPageControl;@end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; //初始化scroolview大小為屏幕大小 UIScrollView *rotateScrollView = [[UIScrollView alloc]initWithFrame:self.view.frame]; //設置滾動范圍 rotateScrollView.contentSize = CGSizeMake(CGRectGetWidth(self.view.frame)*3, CGRectGetHeight(self.view.frame)); //設置分頁效果 rotateScrollView.pagingEnabled = YES; //水平滾動條隱藏 rotateScrollView.showsHorizontalScrollIndicator = NO; //添加三個子視圖，uilabel類型 for (int i=0; i<3; i++) { UILabel *subLabel = [[UILabel alloc] initWithFrame:CGRectMake(CGRectGetWidth(self.view.frame)*i, 0, CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame))]; subLabel.tag = 1000+i; subLabel.text = [NSString stringWithFormat:@"我是第%d個視圖",i]; [subLabel setFont:[UIFont systemFontOfSize:80]]; subLabel.adjustsFontSizeToFitWidth = YES; [subLabel setBackgroundColor:[UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1.0]]; [rotateScrollView addSubview:subLabel];  } UILabel *tempLabel = [rotateScrollView viewWithTag:1000]; //為滾動視圖的右邊添加一個視圖，使得它和第一個視圖一模一樣。 UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(CGRectGetWidth(self.view.frame)*3, 0, CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame))]; label.backgroundColor = tempLabel.backgroundColor; label.text = tempLabel.text; label.font = tempLabel.font; label.adjustsFontSizeToFitWidth = YES; [rotateScrollView addSubview:label]; [self.view addSubview:rotateScrollView]; rotateScrollView.tag = 1000; self.myPageControl = [[UIPageControl alloc]initWithFrame:CGRectMake(0, CGRectGetHeight(self.view.frame)-50, CGRectGetWidth(self.view.frame), 50)]; self.myPageControl.numberOfPages = 3; self.myPageControl.currentPage = 0; [self.view addSubview:self.myPageControl];  //啟動定時器 self.rotateTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(changeView) userInfo:nil repeats:YES]; //為滾動視圖指定代理 rotateScrollView.delegate = self;} #pragma mark -- 滾動視圖的代理方法//開始拖拽的代理方法，在此方法中暫停定時器。-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{ NSLog(@"正在拖拽視圖，所以需要將自動播放暫停掉"); //setFireDate：設置定時器在什么時間啟動 //[NSDate distantFuture]:將來的某一時刻 [self.rotateTimer setFireDate:[NSDate distantFuture]];} //視圖靜止時（沒有人在拖拽），開啟定時器，讓自動輪播- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{ //視圖靜止之后，過1.5秒在開啟定時器 //[NSDate dateWithTimeInterval:1.5 sinceDate:[NSDate date]] 返回值為從現在時刻開始 再過1.5秒的時刻。 NSLog(@"開啟定時器"); [self.rotateTimer setFireDate:[NSDate dateWithTimeInterval:1.5 sinceDate:[NSDate date]]];}  //定時器的回調方法 切換界面- (void)changeView{ //得到scrollView UIScrollView *scrollView = [self.view viewWithTag:1000]; //通過改變contentOffset來切換滾動視圖的子界面 float offset_X = scrollView.contentOffset.x; //每次切換一個屏幕 offset_X += CGRectGetWidth(self.view.frame);  //說明要從最右邊的多余視圖開始滾動了，最右邊的多余視圖實際上就是第一個視圖。所以偏移量需要更改為第一個視圖的偏移量。 if (offset_X > CGRectGetWidth(self.view.frame)*3) { scrollView.contentOffset = CGPointMake(0, 0);  } //說明正在顯示的就是最右邊的多余視圖，最右邊的多余視圖實際上就是第一個視圖。所以pageControl的小白點需要在第一個視圖的位置。 if (offset_X == CGRectGetWidth(self.view.frame)*3) { self.myPageControl.currentPage = 0; }else{ self.myPageControl.currentPage = offset_X/CGRectGetWidth(self.view.frame); }  //得到最終的偏移量 CGPoint resultPoint = CGPointMake(offset_X, 0); //切換視圖時帶動畫效果 //最右邊的多余視圖實際上就是第一個視圖，現在是要從第一個視圖向第二個視圖偏移，所以偏移量為一個屏幕寬度 if (offset_X >CGRectGetWidth(self.view.frame)*3) { self.myPageControl.currentPage = 1; [scrollView setContentOffset:CGPointMake(CGRectGetWidth(self.view.frame), 0) animated:YES]; }else{ [scrollView setContentOffset:resultPoint animated:YES]; } } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated.}  @end