iOS刷帧动画

Posted 2020-06-07

 1 @implementation NJView
 2 
 3 /*
 4 -(void)awakeFromNib
 5 {
 6 
 7     NSLog(@"awakeFromNib");
 8     // 创建CADisplayLink, 默认每秒60次
 9     CADisplayLink *display = [CADisplayLink displayLinkWithTarget:self selector:@selector(updataImage)];
10     // 将CADisplayLink加入到消息循环中
11     [display addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
12 }
13  */
14 
15 
16 - (id)initWithCoder:(NSCoder *)aDecoder
17 {
18     if (self = [super initWithCoder:aDecoder]) {
19         NSLog(@"initWithCoder");
20         
21         // NSTimer一般用于定时的更新一些非界面上的数据
22 //        [NSTimer scheduledTimerWithTimeInterval:
23 //         0.1 target:self selector:@selector(updataImage) userInfo:nil repeats:YES];
24  
25         // 创建CADisplayLink, 默认每秒60次
26         CADisplayLink *display = [CADisplayLink displayLinkWithTarget:self selector:@selector(updataImage)];
27         // 将CADisplayLink加入到消息循环中
28         [display addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
29         
30     }
31     return self;
32 }
33 
34 - (void)updataImage
35 {
36     [self setNeedsDisplay];
37 }
38 
39 
40 - (void)drawRect:(CGRect)rect
41 {
42     CGContextRef ctx = UIGraphicsGetCurrentContext();
43 //    CGContextClearRect(ctx, rect);
44     
45     self.imageY += 10;
46     
47     if (self.imageY > rect.size.height) {
48         self.imageY = 0;
49     }
50     // Drawing code
51     UIImage *image = [UIImage imageNamed:@"snow"];
52     [image   drawAtPoint:CGPointMake(10, self.imageY)];
53     
54     
55 }