//// 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