UIScrollView------2常见代理使用

1.常见代理方法

UIScrollView常见代理方法,放大缩小实例讲解实现。

 1 #import "ViewController.h"
 2
 3 @interface ViewController ()<UIScrollViewDelegate>
 4 @property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
 5 @property (weak, nonatomic) IBOutlet UIImageView *image;
 6
 7 @end
 8
 9 @implementation ViewController
10
11 - (void)viewDidLoad {
12     [super viewDidLoad];
13     _scrollView.delegate = self;
14     _scrollView.contentSize = CGSizeMake(1440, 900);
15     //设置放缩的比例
16     _scrollView.minimumZoomScale = 0.5;
17     _scrollView.maximumZoomScale = 2;
18 }
19
20 #pragma mark UIScrollViewDelegate
21
22 -(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
23     NSLog(@"用户开始拖拽时调用");
24 }
25
26 -(void)scrollViewDidScroll:(UIScrollView *)scrollView{
27     NSLog(@"具体滚动到某个位置时调用");
28     NSLog(@"%@",NSStringFromCGPoint(_scrollView.contentOffset));
29 }
30
31 -(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
32     NSLog(@"停止拖拽时调用");
33 }
34
35 -(void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view{
36     NSLog(@"开始拖动");
37 }
38
39 -(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
40     return _image;
41 }
42
43 -(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale{
44     NSLog(@"正在拖动");
45 }
46
47 @end

2综合运用，广告Banner

(1)首先加一个UIScrollView，设置320*200，再拖入一个UIPageControl在UIScrollView的上方，并设置当前颜色，和点的个数

代码，1.设置banner的contentSize确定滚动范围 2.将3张图片依次添加到banner中，只需处理x的坐标 3.banner的分页属性设置为YES

 1 #import "ViewController.h"
 2
 3 @interface ViewController ()
 4 //滚动栏
 5 @property (weak, nonatomic) IBOutlet UIScrollView *banner;
 6 //分页
 7 @property (weak, nonatomic) IBOutlet UIPageControl *pageContrl;
 8
 9 @end
10
11 @implementation ViewController
12
13 - (void)viewDidLoad {
14     [super viewDidLoad];
15     //设置滚动范围
16     _banner.contentSize = CGSizeMake(320*3, 200);
17     //分页
18     _banner.pagingEnabled = YES;
19     //隐藏底部指示器
20     _banner.showsHorizontalScrollIndicator = NO;
21     //初始化图片 并添加到banner中
22     for(int i=0;i<3;i++){
23         UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:[NSString stringWithFormat:@"image_%d.jpg",i+1]]];
24         imageView.frame = CGRectMake(i*320, 0, 320, 200);
25         [_banner addSubview:imageView];
26     }
27 }

效果

此时UIPageControl的点并不会随着图片的拖动变化而变化，要使U点跟着变化

1.实现UIScrollView的-(void)scrollViewDidScroll:(UIScrollView *)scrollView方法

2.在步骤1方法中通过banner的contentOffset获取移动的坐标，知道移动到了那里

3.通过(contentoffset.x + scrollView/2)/scrollView宽度算出页面

 1 #import "ViewController.h"
 2
 3 @interface ViewController ()<UIScrollViewDelegate>
 4 //滚动栏
 5 @property (weak, nonatomic) IBOutlet UIScrollView *banner;
 6 //分页
 7 @property (weak, nonatomic) IBOutlet UIPageControl *pageContrl;
 8
 9 @end
10
11 @implementation ViewController
12
13 - (void)viewDidLoad {
14     [super viewDidLoad];
15     //设置滚动范围
16     _banner.contentSize = CGSizeMake(320*3, 200);
17     //分页
18     _banner.pagingEnabled = YES;
19     //隐藏底部指示器
20     _banner.showsHorizontalScrollIndicator = NO;
21     //初始化图片 并添加到banner中
22     for(int i=0;i<3;i++){
23         UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:[NSString stringWithFormat:@"image_%d.jpg",i+1]]];
24         imageView.frame = CGRectMake(i*320, 0, 320, 200);
25         [_banner addSubview:imageView];
26     }
27     //设置代理
28     _banner.delegate = self;
29 }
30 #pragma makr UIScrollViewDelegate
31 -(void)scrollViewDidScroll:(UIScrollView *)scrollView{
32     NSLog(@"正在滚动");
33     //计算页面
34     //页码（contentoffset.x + scrollView宽度/2）/scrollView宽度，这里利用UIScrollView分页机制
35     CGFloat bannerW = _banner.frame.size.width;
36     CGFloat x = _banner.contentOffset.x;
37     //页码
38     int page = (x + bannerW/2)/bannerW;
39     _pageContrl.currentPage = page;
40 }
41
42 @end