ios 使 UIView 透明
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Making UIView transparent
提问by peter1234
I want to add a UIView to my UIViewController but I want it to be transparent until I decide to create an Oval inside the UIView.
我想向我的 UIViewController 添加一个 UIView，但我希望它是透明的，直到我决定在 UIView 中创建一个椭圆。
Until I create the oval, I can set my view's alpha to 0 but when I want to add the oval, the background color is still black.
在创建椭圆之前，我可以将视图的 alpha 设置为 0，但是当我想添加椭圆时，背景颜色仍然是黑色。
here's what it looks like with a bunch of ovals
这是一堆椭圆的样子
In my UIView:
在我的 UIView 中：
- (void)drawRect:(CGRect)rect
{
[self pushContext];
UIBezierPath *oval = [UIBezierPath bezierPathWithOvalInRect:self.bounds];
[[UIColor redColor] setFill];
[oval fill];
self.opaque = NO;
[self setBackgroundColor:[UIColor clearColor]];
[oval addClip];
[self setBackgroundColor:[UIColor clearColor]];
[self popContext];
}
回答by Dharmbir Singh
Please try to use this one
请尝试使用这个
view.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.0];
view.opaque = NO;
回答by Guo Luchuan
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
self.opaque = NO;
}
return self;
}
- (void)drawRect:(CGRect)rect
{
[[UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:0.0] setFill];
UIRectFill(rect);
[self pushContext];
UIBezierPath *oval = [UIBezierPath bezierPathWithOvalInRect:self.bounds];
[[UIColor redColor] setFill];
[oval fill];
[oval addClip];
[self popContext];
}
回答by Natasha
In your ViewController, you could say that opaque is NO. Let's say, your view is named myCustomView.
在您的 ViewController 中，您可以说 opaque 为 NO。假设您的视图名为 myCustomView。
- (void)viewDidLoad {
[super viewDidLoad];
self.myCustomView.opaque = NO;
}
Or you could just go to the storyboard and uncheck the opaque checkbox like-
或者您可以直接转到故事板并取消选中不透明的复选框，例如-
回答by Matt
In Swift 3.x: (where layeris the view)
在 Swift 3.x 中：（层是视图）
layer.backgroundColor = UIColor.clear.cgColor
layer.isOpaque = false
回答by Northern Captain
I did semi-transparent background for my UIViewController the same way as it's recommended here but it didn't work until I set modalPresentationStyleto .custom
我为我的 UIViewController 做了半透明背景与这里推荐的相同，但直到我将modalPresentationStyle设置为.custom才起作用
my Swift 4code:
我的Swift 4代码：
modalPresentationStyle = .custom
view.isOpaque = false
view.backgroundColor = UIColor.black.withAlphaComponent(0.2)
I open my controller from another one using present(controller, anim, completion) method.
我使用present（控制器，动画，完成）方法从另一个控制器打开我的控制器。
