基于Yuchen版本的简单swift视图

class GradientView: UIView {
    override class func layerClass() -> AnyClass { return CAGradientLayer.self }

    lazy var gradientLayer: CAGradientLayer = {
        return self.layer as! CAGradientLayer
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

}

然后你可以在初始化后使用gradientLayer，像这样…

someView.gradientLayer.colors = [UIColor.whiteColor().CGColor, UIColor.blackColor().CGColor]

基于Yuchen版本的简单swift视图

class GradientView: UIView {
    override class func layerClass() -> AnyClass { return CAGradientLayer.self }

    lazy var gradientLayer: CAGradientLayer = {
        return self.layer as! CAGradientLayer
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

}

然后你可以在初始化后使用gradientLayer，像这样…

someView.gradientLayer.colors = [UIColor.whiteColor().CGColor, UIColor.blackColor().CGColor]

这是我推荐的方法。

为了提高可重用性，我建议创建一个CAGradientLayer类别，并添加所需的渐变作为类方法。在头文件中像这样指定它们:

#import <QuartzCore/QuartzCore.h>

@interface CAGradientLayer (SJSGradients)

+ (CAGradientLayer *)redGradientLayer;
+ (CAGradientLayer *)blueGradientLayer;
+ (CAGradientLayer *)turquoiseGradientLayer;
+ (CAGradientLayer *)flavescentGradientLayer;
+ (CAGradientLayer *)whiteGradientLayer;
+ (CAGradientLayer *)chocolateGradientLayer;
+ (CAGradientLayer *)tangerineGradientLayer;
+ (CAGradientLayer *)pastelBlueGradientLayer;
+ (CAGradientLayer *)yellowGradientLayer;
+ (CAGradientLayer *)purpleGradientLayer;
+ (CAGradientLayer *)greenGradientLayer;

@end

然后在你的实现文件中，用下面的语法指定每个渐变:

+ (CAGradientLayer *)flavescentGradientLayer
{
    UIColor *topColor = [UIColor colorWithRed:1 green:0.92 blue:0.56 alpha:1];
    UIColor *bottomColor = [UIColor colorWithRed:0.18 green:0.18 blue:0.18 alpha:1];

    NSArray *gradientColors = [NSArray arrayWithObjects:(id)topColor.CGColor, (id)bottomColor.CGColor, nil];
    NSArray *gradientLocations = [NSArray arrayWithObjects:[NSNumber numberWithInt:0.0],[NSNumber numberWithInt:1.0], nil];

    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.colors = gradientColors;
    gradientLayer.locations = gradientLocations;

    return gradientLayer;
}

然后简单地将这个类别导入你的ViewController或任何其他所需的子类，并像这样使用它:

CAGradientLayer *backgroundLayer = [CAGradientLayer purpleGradientLayer];
backgroundLayer.frame = self.view.frame;
[self.view.layer insertSublayer:backgroundLayer atIndex:0];

调用上面的解决方案来更新层是一个好主意

viewDidLayoutSubviews 

正确地更新视图

我的解决方案是创建具有CAGradientLayer可访问的UIView子类作为只读属性。这将允许你自定义你想要的渐变，你不需要自己处理布局变化。子类实现:

@interface GradientView : UIView

@property (nonatomic, readonly) CAGradientLayer *gradientLayer;

@end

@implementation GradientView

+ (Class)layerClass
{
    return [CAGradientLayer class];
}

- (CAGradientLayer *)gradientLayer
{
    return (CAGradientLayer *)self.layer;
}

@end

用法:

self.iconBackground = [GradientView new];
[self.background addSubview:self.iconBackground];
self.iconBackground.gradientLayer.colors = @[(id)[UIColor blackColor].CGColor, (id)[UIColor whiteColor].CGColor];
self.iconBackground.gradientLayer.startPoint = CGPointMake(1.0f, 1.0f);
self.iconBackground.gradientLayer.endPoint = CGPointMake(0.0f, 0.0f);

我已经在代码中实现了这一点。

UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, self.view.frame.size.width, 31.0f)];
view1.backgroundColor = [UIColor clearColor];
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = view1.bounds;
UIColor *topColor = [UIColor colorWithRed:132.0/255.0 green:222.0/255.0 blue:109.0/255.0 alpha:1.0];
UIColor *bottomColor = [UIColor colorWithRed:31.0/255.0 green:150.0/255.0 blue:99.0/255.0 alpha:1.0];
gradient.colors = [NSArray arrayWithObjects:(id)[topColor CGColor], (id)[bottomColor CGColor], nil];


[view1.layer insertSublayer:gradient atIndex:0];

现在我可以在视图中看到渐变。