我试图在运行时生成一个渐变颜色背景(纯色到透明)的视图。有办法做到吗?
当前回答
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);
其他回答
extension UIView {
func applyGradient(isVertical: Bool, colorArray: [UIColor]) {
layer.sublayers?.filter({ $0 is CAGradientLayer }).forEach({ $0.removeFromSuperlayer() })
let gradientLayer = CAGradientLayer()
gradientLayer.colors = colorArray.map({ $0.cgColor })
if isVertical {
//top to bottom
gradientLayer.locations = [0.0, 1.0]
} else {
//left to right
gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5)
gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5)
}
backgroundColor = .clear
gradientLayer.frame = bounds
layer.insertSublayer(gradientLayer, at: 0)
}
}
使用
someView.applyGradient(isVertical: true, colorArray: [.green, .blue])
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
因为我只需要一种类型的梯度在我的应用程序,我创建了一个子类的UIView和预配置梯度层初始化固定的颜色。 UIView的初始化器调用configuregradientlayer -方法,它配置CAGradientLayer:
DDGradientView.h:
#import <UIKit/UIKit.h>
@interface DDGradientView : UIView {
}
@end
DDGradientView.m:
#import "DDGradientView.h"
@implementation DDGradientView
// Change the views layer class to CAGradientLayer class
+ (Class)layerClass
{
return [CAGradientLayer class];
}
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
self = [super initWithCoder:aDecoder];
if(self) {
[self configureGradientLayer];
}
return self;
}
- (instancetype)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if(self) {
[self configureGradientLayer];
}
return self;
}
// Make custom configuration of your gradient here
- (void)configureGradientLayer {
CAGradientLayer *gLayer = (CAGradientLayer *)self.layer;
gLayer.colors = [NSArray arrayWithObjects:(id)[[UIColor whiteColor] CGColor], (id)[[UIColor lightGrayColor] CGColor], nil];
}
@end
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]
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);
推荐文章
- 首先添加一个UIView,甚至是导航栏
- 我如何改变UIButton标题颜色?
- 在Swift中如何调用GCD主线程上的参数方法?
- NSLayoutConstraints是可动画的吗?
- iOS -构建失败,CocoaPods无法找到头文件
- CFNetwork SSLHandshake iOS 9失败
- 请求失败:不可接受的内容类型:文本/html使用AFNetworking 2.0
- 缺少推荐的图标文件-该包不包含iPhone / iPod Touch的应用程序图标,像素为“120x120”,png格式
- 以编程方式创建segue
- 如何使用Xcode创建。ipa文件?
- 动态改变UILabel的字体大小
- 在iPhone上确定用户是否启用了推送通知
- 是否有可能禁用浮动头在UITableView与UITableViewStylePlain?
- 错误ITMS-9000:“冗余二进制文件上传。火车1.0版本已经有一个二进制版本上传。
- Swift -转换为绝对值