ScrollView高级特性

Posted 2020-10-08 vector11248

 1 - (void)viewDidLoad {
 2     [super viewDidLoad];
 3     //滚动视图，可以对屏幕内容进行滚屏查看。
 4     
 5     _scrollView = [[UIScrollView alloc]init];
 6     
 7     _scrollView.frame = CGRectMake(10, 50, 300, 400);
 8     
 9     _scrollView.bounces = YES;
10     
11     //是否允许通过点击屏幕让滚动视图响应事件
12     _scrollView.userInteractionEnabled = YES;
13     
14     //设置画布大小，纵向效果
15     _scrollView.contentSize = CGSizeMake(300, 400*3);
16     
17     
18     for(int i=0 ;i<3;i++)
19     {
20         //生成图片名称
21         NSString* strName = [NSString stringWithFormat:@"%d.jpg",i+1];
22         
23         UIImage* image = [UIImage imageNamed:strName];
24         
25         //创建视图对象
26         UIImageView* iView = [[UIImageView alloc]init];
27         //图像赋值
28         iView.image = image;
29         //设置图像试图在滚动视图画布中的位置
30         iView.frame = CGRectMake(0, 400*i, 300, 400);
31         
32         [_scrollView addSubview:iView];
33         
34     }
35     
36     [self.view addSubview:_scrollView];
37     
38     //取消按页滚动效果
39     _scrollView.pagingEnabled = NO;
40     
41     //滚动视图画布的移动位置，偏移位置
42     _scrollView.contentOffset = CGPointMake(0, 0);
43     //将当前视图控制器作为代理对象
44     _scrollView.delegate = self;
45     
46 }
47 
48 -(void) touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
49 {
50 //    _scrollView.contentOffset = CGPointMake(0, 0);
51     
52     //带有动画效果的，移动到指定位置
53     
54     [_scrollView scrollRectToVisible:CGRectMake(0, 600, 300, 400) animated:YES];
55     
56 }
57 
58 
59 //可以使用此函数，监控滚动视图的位置
60 -(void) scrollViewDidScroll:(UIScrollView *)scrollView
61 {
62     NSLog(@"y = %f",scrollView.contentOffset.y);
63 }
64 
65 //由此，我在这里总结一共几个事件
66 //拖动：即将开始拖动，即将结束拖动，已经结束拖动。后两者是连贯的
67 //减速：即将开始减速，已经结束减速
68 -(void) scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
69 {
70     NSLog(@"已经结束拖动");
71 }
72 
73 -(void) scrollViewWillBeginDragging:(UIScrollView *)scrollView
74 {
75     NSLog(@"即将开始拖动");
76 }
77 
78 -(void) scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
79 {
80     NSLog(@"即将结束拖动");
81 }
82 
83 -(void) scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
84 {
85     NSLog(@"视图即将开始减速");
86 }
87 
88 //视图停止时调用
89 -(void) scrollViewDidEndDecelerating:(UIScrollView *)scrollView
90 {
91     NSLog(@"视图已经结束减速");
92 }

1 @interface ViewController : UIViewController<UIScrollViewDelegate>
2 {
3     //当前视图控制器要实现的协议函数
4     //定义一个滚动视图成员变量
5     UIScrollView* _scrollView;
6     
7     
8 }