渐变色效果demo

#import "ViewController.h"

@interface ViewController ()

@property (strong, nonatomic) CAGradientLayer *gradientLayer;

@property (strong, nonatomic) NSTimer *timer;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

//初始化imageView

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image"]];

imageView.frame = CGRectMake(0, 0, self.view.bounds.size.width, 200);

imageView.center = self.view.center;

[self.view addSubview:imageView];

//初始化渐变层

self.gradientLayer = [CAGradientLayer layer];

self.gradientLayer.frame = imageView.bounds;

[imageView.layer addSublayer:self.gradientLayer];

//设置渐变颜色方向

self.gradientLayer.startPoint = CGPointMake(0, 0);

self.gradientLayer.endPoint = CGPointMake(0, 1);

//设定颜色组

self.gradientLayer.colors = @[(__bridge id)[UIColor clearColor].CGColor,

(__bridge id)[UIColor purpleColor].CGColor];

//设定颜色分割点

self.gradientLayer.locations = @[@(0.5f) ,@(1.0f)];

//定时器

//    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0f

//                                                  target:self

//                                                selector:@selector(TimerEvent)

//                                                userInfo:nil

//                                                repeats:YES];

}

- (void)TimerEvent

{

//定时改变颜色

self.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];

//定时改变分割点

self.gradientLayer.locations = @[@(arc4random() % 10 / 10.0f), @(1.0f)];

}

@end