1 - (void)viewDidLoad
2 {
3 [super viewDidLoad];
4 [self.view setBackgroundColor:[UIColor grayColor]];
5 // Do any additional setup after loading the view, typically from a nib.
6 MarqueeLabel *label = [[MarqueeLabel alloc]initWithFrame:CGRectMake(0, 0, 100, 20)];
7 label.backgroundColor = [UIColor clearColor];
8
9 float fadeLength = 15.0f;
10 CAGradientLayer* gradientMask = [CAGradientLayer layer];
11 gradientMask.bounds = label.layer.bounds;
12 gradientMask.position = CGPointMake([label bounds].size.width / 2, [label bounds].size.height / 2);
13 NSObject *transparent = (NSObject*) [[UIColor clearColor] CGColor];
14 NSObject *opaque = (NSObject*) [[UIColor blackColor] CGColor];
15 gradientMask.startPoint = CGPointMake(0.0, CGRectGetMidY(label.frame));
16 gradientMask.endPoint = CGPointMake(1.0, CGRectGetMidY(label.frame));
17 float fadePoint = fadeLength/label.frame.size.width;
18 [gradientMask setColors: [NSArray arrayWithObjects: transparent, opaque, opaque, transparent, nil]];
19 [gradientMask setLocations: [NSArray arrayWithObjects:
20 [NSNumber numberWithFloat: 0.0],
21 [NSNumber numberWithFloat: fadePoint],
22 [NSNumber numberWithFloat: 1 - fadePoint],
23 [NSNumber numberWithFloat: 1.0],
24 nil]];
25 label.layer.mask = gradientMask;
26
27 label.text = @"者是一个测试程序测试长度适用的滚动的是就是";
28 [self.view addSubview:label];
29 }
