ios基础篇（二十三）—— 定时器NSTimer与图片的自动切换

  1 @interface ViewController ()<UIScrollViewDelegate>{
  2 
  3     UIPageControl *pageCtrl;
  4     UIScrollView *scrollView;
  5     NSArray *imageArray;
  6     
  7     NSTimer *timer;
  8     int lastPage;
  9     int currentPage;
 10 
 11 }
 12 
 13 @end
 14 
 15 @implementation ViewController
 16 
 17 - (void)viewDidLoad {
 18     [super viewDidLoad];
 19     // Do any additional setup after loading the view, typically from a nib.
 20     float width = self.view.frame.size.width;
 21     
 22     //创建UIScrollView
 23     scrollView = [[UIScrollView alloc] initWithFrame:(CGRect){0,20,width,160}];
 24     scrollView.delegate = self;
 25     scrollView.pagingEnabled = YES;
 26     scrollView.contentSize = CGSizeMake(width*5, 160);
 27     scrollView.showsHorizontalScrollIndicator = NO;
 28     scrollView.showsVerticalScrollIndicator = NO;
 29     [self.view addSubview:scrollView];
 30     
 31     //开启定时器方法
 32     [self timeOn];
 33     
 34     //创建UIPageControl
 35     pageCtrl = [[UIPageControl alloc] initWithFrame:(CGRect){0,160,width,20}];
 36     [self.view addSubview:pageCtrl];
 37     pageCtrl.numberOfPages = 5;
 38     pageCtrl.currentPageIndicatorTintColor = [UIColor grayColor];
 39     pageCtrl.pageIndicatorTintColor = [UIColor colorWithWhite:0.8 alpha:1];
 40     [pageCtrl addTarget:self action:@selector(pageAction:) forControlEvents:UIControlEventTouchUpInside];
 41     
 42     
 43     float imageWidth = width-15;
 44     float imageHeight = 150;
 45     
 46     imageArray =@[@"tu3", @"tu1", @"tu2", @"tu4", @"tu5"];
 47     
 48     //遍历imageArray数组，添加图片到UIScrollView
 49     for (int i=0; i<imageArray.count; i++) {
 50         NSString *image = [imageArray objectAtIndex:i];
 51         
 52         ScrollPageView *images = [[ScrollPageView alloc] initWithFrame:(CGRect){4+width*0.5*i,3,imageWidth,imageHeight} setImage:[UIImage imageNamed:image]];
 53         [scrollView addSubview:images];
 54     }
 55 }
 56 
 57 //实现图片自动切换
 58 - (void)changeImage{
 59     currentPage = lastPage+1;
 60     [scrollView setContentOffset:(CGPoint){currentPage*375,0} animated:YES];
 61     lastPage =currentPage;
 62     if (lastPage>3) {
 63         lastPage =-1;
 64     }
 65 }
 66 
 67 - (void)scrollViewDidScroll:(UIScrollView *)ScrollView{
 68     int page = scrollView.contentOffset.x/scrollView.frame.size.width;
 69     pageCtrl.currentPage = page;
 70 }
 71 
 72 //将要开始拖拽关闭定时器
 73 - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
 74     [self timeOff];
 75 }
 76 
 77 //结束拖拽开启定时器
 78 - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
 79     [self timeOn];
 80 }
 81 
 82 //开启定时器
 83 - (void)timeOn{
 84     
 85     timer = [NSTimer scheduledTimerWithTimeInterval:1
 86                                              target:self
 87                                            selector:@selector(changeImage)
 88                                            userInfo:nil
 89                                             repeats:YES];
 90     
 91     [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
 92 }
 93 
 94 //关闭定时器
 95 - (void)timeOff{
 96     
 97     [timer invalidate];
 98     timer = nil;
 99 }
100 
101 - (void)pageAction:(UIPageControl*)page{
102     int pageNum =(int)pageCtrl.currentPage;
103     CGSize size = scrollView.frame.size;
104     [scrollView setContentOffset:(CGPoint){(pageNum+1)*size.width,0} animated:YES];
105     [timer invalidate];
106 }