#import "ViewController.h"
@interface ViewController ()
{
CAGradientLayer *_gradientLayer;
}
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
UIImageView *_imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"1"]];
_imageView.center = self.view.center;
[self.view addSubview:_imageView];
_gradientLayer = [CAGradientLayer layer];
_gradientLayer.frame = _imageView.bounds;
/**设置渐变方向*/
_gradientLayer.startPoint = CGPointMake(0, 0);
_gradientLayer.endPoint = CGPointMake(0, 1);
/**设置颜色*/
_gradientLayer.colors = @[ (__bridge id)[UIColor clearColor].CGColor,
(__bridge id)[UIColor redColor].CGColor
];
/**设置颜色分割点*/
_gradientLayer.locations = @[@(0.5),@(1.0f)];
[_imageView.layer addSublayer:_gradientLayer];
[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timerEvent) userInfo:nil repeats:YES];
}
- (void)timerEvent
{
_gradientLayer.colors = @[ (__bridge id)[UIColor clearColor].CGColor,
(__bridge id)[UIColor colorWithRed:arc4random()%255/255.0
green:arc4random()%255/255.0
blue:arc4random()%255/255.0
alpha:1.0].CGColor
];
}