效果如下：
本人已经将实现封装到一个分类里面，可以直接调用：
// label
UILabel *glowLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, self.view.width, 40)];
glowLabel.center = self.view.center;
glowLabel.text = @"LeiLuRong...";
glowLabel.textAlignment = NSTextAlignmentCenter;
glowLabel.textColor = [UIColor whiteColor];
glowLabel.font = [UIFont systemFontOfSize:28];
[self.view addSubview:glowLabel];
glowLabel.glowRadius = @(2.f);
glowLabel.glowOpacity = @(1.f);
glowLabel.glowColor = [UIColor cyanColor];
glowLabel.glowDuration = @(1.f);
glowLabel.hideDuration = @(0.3);
glowLabel.glowAnimationDuration = @(1.5f);
[glowLabel createGlowLayer];
[glowLabel insertGlowLayer];
[glowLabel startGlowLoop];
// imageView
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
imageView.center = CGPointMake(self.view.center.x, 400);
imageView.image = [UIImage imageNamed:@"collection_new"];
[self.view addSubview:imageView];
imageView.glowRadius = @(2.f);
imageView.glowOpacity = @(0.5f);
imageView.glowColor = [UIColor whiteColor];
imageView.glowDuration = @1.5;
imageView.hideDuration = @0.5;
imageView.glowAnimationDuration = @1.5;
[imageView createGlowLayer];
[imageView insertGlowLayer];
[imageView startGlowLoop];
分类：
UIView+GlowView.h
/**
* 辉光的颜色
*/
@property (nonatomic, strong) UIColor *glowColor;
/**
* 辉光的透明度
*/
@property (nonatomic, strong) NSNumber *glowOpacity;
/**
* 辉光的阴影半径
*/
@property (nonatomic, strong) NSNumber *glowRadius;
#pragma mark - 设置辉光时间间隔
/**
* 一次完整的辉光周期（从显示到透明或者从透明到显示），默认1s
*/
@property (nonatomic, strong) NSNumber *glowAnimationDuration;
/**
* 保持辉光时间（不设置，默认为0.5s）
*/
@property (nonatomic, strong) NSNumber *glowDuration;
/**
* 不显示辉光的周期（不设置默认为0.5s）
*/
@property (nonatomic, strong) NSNumber *hideDuration;
#pragma mark - 辉光相关操作
/**
* 创建出辉光layer
*/
- (void)createGlowLayer;
/**
* 插入辉光的layer
*/
- (void)insertGlowLayer;
/**
* 移除辉光的layer
*/
- (void)removeGlowLayer;
/**
* 显示辉光
*/
- (void)glowToshowAnimated:(BOOL)animated;
/**
* 隐藏辉光
*/
- (void)glowToHideAnimated:(BOOL)animated;
/**
* 开始循环辉光
*/
- (void)startGlowLoop;
UIView+GlowView.m
#import "UIView+GlowView.h"
#import <objc/runtime.h>
@interface UIView ()
@property (nonatomic, strong) CALayer *glowLayer;
@property (nonatomic, strong) dispatch_source_t dispatchSource;
@end
@implementation UIView (GlowView)
- (void)createGlowLayer {
UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);
[self.layer renderInContext:UIGraphicsGetCurrentContext()];
UIBezierPath* path = [UIBezierPath bezierPathWithRect:self.bounds];
[[self accessGlowColor] setFill];
[path fillWithBlendMode:kCGBlendModeSourceAtop alpha:1.0];
self.glowLayer = [CALayer layer];
self.glowLayer.frame = self.bounds;
self.glowLayer.contents = (__bridge id)UIGraphicsGetImageFromCurrentImageContext().CGImage;
self.glowLayer.opacity = 0.f;
self.glowLayer.shadowOffset = CGSizeMake(0, 0);
self.glowLayer.shadowOpacity = 1.f;
UIGraphicsEndImageContext();
}
- (void)insertGlowLayer {
if (self.glowLayer) {
[self.layer addSublayer:self.glowLayer];
}
}
- (void)removeGlowLayer {
if (self.glowLayer) {
[self.glowLayer removeFromSuperlayer];
}
}
- (void)glowToshowAnimated:(BOOL)animated {
self.glowLayer.shadowColor = [self accessGlowColor].CGColor;
self.glowLayer.shadowRadius = [self accessGlowRadius].floatValue;
if (animated) {
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];
animation.fromValue = @(0.f);
animation.toValue = [self accessGlowOpacity];
self.glowLayer.opacity = [self accessGlowOpacity].floatValue;
animation.duration = [self accessAnimationDuration].floatValue;
[self.glowLayer addAnimation:animation forKey:@"glowLayerOpacity"];
} else {
[self.glowLayer removeAnimationForKey:@"glowLayerOpacity"];
self.glowLayer.opacity = [self accessGlowOpacity].floatValue;
}
}
- (void)glowToHideAnimated:(BOOL)animated {
self.glowLayer.shadowColor = [self accessGlowColor].CGColor;
self.glowLayer.shadowRadius = [self accessGlowRadius].floatValue;
if (animated) {
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];
animation.fromValue = [self accessGlowOpacity];
animation.toValue = @(0.f);
self.glowLayer.opacity = 0.f;
animation.duration = [self accessAnimationDuration].floatValue;
[self.glowLayer addAnimation:animation forKey:@"glowLayerOpacity"];
} else {
[self.glowLayer removeAnimationForKey:@"glowLayerOpacity"];
self.glowLayer.opacity = 0.f;
}
}
- (void)startGlowLoop {
if (self.dispatchSource == nil) {
CGFloat seconds = [self accessAnimationDuration].floatValue * 2 + [self accessGlowDuration].floatValue + [self accessHideDuration].floatValue;
CGFloat delaySeconds = [self accessAnimationDuration].floatValue + [self accessGlowDuration].floatValue;
self.dispatchSource = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
__weak UIView *weakSelf = self;
dispatch_source_set_timer(self.dispatchSource, dispatch_time(DISPATCH_TIME_NOW, 0), NSEC_PER_SEC * seconds, 0);
dispatch_source_set_event_handler(self.dispatchSource, ^{
[weakSelf glowToshowAnimated:YES];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC * delaySeconds), dispatch_get_main_queue(), ^{
[weakSelf glowToHideAnimated:YES];
});
});
dispatch_resume(self.dispatchSource);
}
}
#pragma mark - 处理数据越界问题
- (NSNumber *)accessGlowOpacity {
if (self.glowOpacity) {
if (self.glowOpacity.floatValue <= 0 || self.glowOpacity.floatValue > 1) {
return @(0.8);
} else {
return self.glowOpacity;
}
} else {
return @(0.8);
}
}
- (NSNumber *)accessGlowDuration {
if (self.glowDuration) {
if (self.glowDuration.floatValue <= 0) {
return @(0.5f);
} else {
return self.glowDuration;
}
} else {
return @(0.5f);
}
}
- (NSNumber *)accessHideDuration {
if (self.hideDuration) {
if (self.hideDuration.floatValue < 0) {
return @(0.5);
} else {
return self.hideDuration;
}
} else {
return @(0.5f);
}
}
- (NSNumber *)accessAnimationDuration {
if (self.glowAnimationDuration) {
if (self.glowAnimationDuration.floatValue <= 0) {
return @(1.f);
} else {
return self.glowAnimationDuration;
}
} else {
return @(1.f);
}
}
- (UIColor *)accessGlowColor {
if (self.glowColor) {
return self.glowColor;
} else {
return [UIColor redColor];
}
}
- (NSNumber *)accessGlowRadius {
if (self.glowRadius) {
if (self.glowRadius.floatValue <= 0) {
return @(2.f);
} else {
return self.glowRadius;
}
} else {
return @(2.f);
}
}
#pragma mark - runtime属性
- (void)setDispatchSource:(dispatch_source_t)dispatchSource {
objc_setAssociatedObject(self, @selector(dispatchSource), dispatchSource, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (dispatch_source_t)dispatchSource {
return objc_getAssociatedObject(self, _cmd);
}
- (void)setGlowColor:(UIColor *)glowColor {
objc_setAssociatedObject(self, @selector(glowColor), glowColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (UIColor *)glowColor {
return objc_getAssociatedObject(self, _cmd);
}
- (void)setGlowOpacity:(NSNumber *)glowOpacity {
objc_setAssociatedObject(self, @selector(glowOpacity), glowOpacity, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSNumber *)glowOpacity {
return objc_getAssociatedObject(self, _cmd);
}
- (void)setGlowRadius:(NSNumber *)glowRadius {
objc_setAssociatedObject(self, @selector(glowRadius), glowRadius, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSNumber *)glowRadius {
return objc_getAssociatedObject(self, _cmd);
}
- (void)setGlowAnimationDuration:(NSNumber *)glowAnimationDuration {
objc_setAssociatedObject(self, @selector(glowAnimationDuration), glowAnimationDuration, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSNumber *)glowAnimationDuration {
return objc_getAssociatedObject(self, _cmd);
}
- (void)setGlowDuration:(NSNumber *)glowDuration {
objc_setAssociatedObject(self, @selector(glowDuration), glowDuration, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSNumber *)glowDuration {
return objc_getAssociatedObject(self, _cmd);
}
- (void)setHideDuration:(NSNumber *)hideDuration {
objc_setAssociatedObject(self, @selector(hideDuration), hideDuration, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSNumber *)hideDuration {
return objc_getAssociatedObject(self, _cmd);
}
NSString * const _recognizerGlowLayer = @"_recognizerGlowLayer";
- (void)setGlowLayer:(CALayer *)glowLayer {
objc_setAssociatedObject(self, @selector(glowLayer), glowLayer, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (CALayer *)glowLayer {
return objc_getAssociatedObject(self, _cmd);
}
@end
源码已经放在GitHub：https://github.com/Fendouzhe/LRAnimations，有兴趣的欢迎下载查看，有帮助可以star，谢谢！
