在 iOS 的 UIImageView 后面添加 CAGradient 层

Posted 2023-02-23

【中文标题】在 iOS 的 UIImageView 后面添加 CAGradient 层

【英文标题】：Add CAGradient Layer behind UIImageView iOS

【发布时间】：2013-01-30 01:13:50

【问题描述】：

我正在尝试在透明图像后面添加渐变。我在地图 leftCallOutAccessoryView 上执行此操作，但是无论我尝试什么，渐变层始终显示在 imageView 上方并希望它出现在其后面

这是我的 MKAnnotationView 代码，它是一个名为 pinView 的 ivar

pinView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];

UIImageView *profileIconView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Profile.png"]];
pinView.leftCalloutAccessoryView = profileIconView;

CAGradientLayer *backgroundLayer = [CAGradientLayer layer];
backgroundLayer.frame = CGRectMake(0, 0, 30, 30);
backgroundLayer.cornerRadius = 2;
backgroundLayer.borderWidth = 1;
backgroundLayer.borderColor = [UIColor whiteColor].CGColor;
backgroundLayer.colors = [NSArray arrayWithObjects:(id)[[sharedManager cellGradientEnd] CGColor], (id)[[sharedManager cellGradientStart] CGColor], nil];
[profileIconView.layer insertSublayer:backgroundLayer atIndex:0];

【参考方案1】：

我设法用下面的方法弄清楚了，简而言之，我创建了一个空视图，然后将 imageView 作为子视图添加到视图中，现在一切都很好！：

UIView *view = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 30, 30)];
UIImageView *profileIconView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Profile.png"]];
pinView.leftCalloutAccessoryView = view;

CAGradientLayer *backgroundLayer = [CAGradientLayer layer];
backgroundLayer.frame = view.bounds;
backgroundLayer.cornerRadius = 2;
backgroundLayer.borderWidth = 1;
backgroundLayer.borderColor = [UIColor whiteColor].CGColor;
backgroundLayer.colors = [NSArray arrayWithObjects:(id)[[sharedManager cellGradientEnd] CGColor], (id)[[sharedManager cellGradientStart] CGColor], nil];
[pinView.leftCalloutAccessoryView.layer insertSublayer:backgroundLayer atIndex:0];
[view addSubview:profileIconView];