Making UIView transparent

Question

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.

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.

here's what it looks like with a bunch of ovals

In my UIView:

- (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];
}

score 29 · Answer 1 · answered Mar 15 '13 at 05:17

29

Please try to use this one

view.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.0];
view.opaque = NO;

answered Mar 15 '13 at 05:17

Dharmbir Singh

17,485
5
50
66

To make transparent: `view.isOpaque = false` – spencer.sm Mar 17 '18 at 04:57
2

Using `UIColor.clear` will be better choice to standardize the code all over the place. – Cheok Yan Cheng Sep 05 '21 at 13:27

score 18 · Accepted Answer · answered Mar 15 '13 at 05:24

- (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];
}

score 5 · Answer 3 · answered Jan 01 '16 at 14:38

In your ViewController, you could say that opaque is NO. Let's say, your view is named myCustomView.

- (void)viewDidLoad {
    [super viewDidLoad];
    self.myCustomView.opaque = NO;   
}

Or you could just go to the storyboard and uncheck the opaque checkbox like-

score 4 · Answer 4 · answered Sep 15 '18 at 16:09

4

I did semi-transparent background for my UIViewController the same way as it's recommended here but it didn't work until I set modalPresentationStyle to .custom

my Swift 4 code:

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.

answered Sep 15 '18 at 16:09

Northern Captain

1,147
3
25
32

Thanks for the tip. I was scratching my head on this for quite a while until I saw your answer. I changed `modalPresentationStyle` to `.custom` and it worked for me too! – Brian Sachetta Apr 09 '20 at 21:29

score 3 · Answer 5 · answered Aug 07 '18 at 12:44

3

In Swift 3.x: (where layer is the view)

layer.backgroundColor = UIColor.clear.cgColor
layer.isOpaque = false

answered Aug 07 '18 at 12:44

Matt

693
9
16

I got an exception "Unexpectedly found nil while implicitly unwrapping an Optional value" – Pravalika Feb 19 '20 at 22:43
Swift is an evolving language, which version are you using? – Matt Feb 20 '20 at 23:25

Making UIView transparent

5 Answers5