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iOS

Posted by Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

Give a UICollectionViewCell the blur property as a background.

I am attempting to make the background of a UICollectionViewCell blurry/transparent. I am looking at these Stack Overflow posts:

http://stackoverflow.com/questions/24067719/how-to-use-uivisualeffectview http://stackoverflow.com/questions/24424165/how-to-implement-uivisualeffectview-in-uitableview-with-adaptive-segues

I am also watching the video on custom cells from the Photo Bombers app again.

This is what I have so far:

- (id)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {

        UIVisualEffect *blurEffect;
        blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];

        UIVisualEffectView *visualEffectView;
        visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];

        visualEffectView.frame = self.maskView.bounds;
        [UIImageView addSubview:visualEffectView];
    }
}

- (void)layoutSubviews {

    self.maskView.frame = self.contentView.bounds;
}

I am getting an error when I try to add a subview:

No known class method for selector 'addSubview'

2 Answers

Stefan Cimander
Stefan Cimander
37,115 Points

Okay, you don't want to add the effect to an image but to the UICollectionViewCell instead, sorry my mistake.

Try to add the effect view to the instance of the cell like this:

[self addSubview: visualEffectView];

Does it work that way?

Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

It worked! Thanks!

Stefan Cimander
Stefan Cimander
37,115 Points
Stefan Cimander
Stefan Cimander
37,115 Points

I hope I'm getting your problem right, but in order to call addSubview:, you first need an object of type UIView. In this case, there is missing a concrete imageView (of type UIImageView) the visualEffectView should be added to.

Try to replace the line:

[UIImageView addSubview: visualEffectView];

by something like this:

// Use the imageView object instead of UIImageView class:
[imageView addSubview: visualEffectView];
Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

That didn't do it, I got this error:

Unknown receiver 'imageView'; did you mean 'UIImageView'?

You can also use swift if you want.