Getters and setters for UIView

Question

In my UIView subclass' .h:

@interface MyView : UIView
@property (nonatomic, strong) UIImageView *imageView;
@end

I'm setting up the UIImageView on my UIView subclass like this (init method):

self.imageView = [[UIImageView alloc]initWithFrame:CGRectMake(5, 0, 34, 34)];
self.imageView.layer.cornerRadius = CGRectGetWidth(imageView.frame) / 2.0f;
self.imageView.layer.masksToBounds = YES;
self.imageView.backgroundColor = [UIColor someColor];
[self addSubview: self.imageView];

So, I can do myView.imageView.image = [UIImage someImage] and it sets the image on the UIImageView correctly. My problem comes when trying to clean up the code on my UIView subclass.

I'm trying to do this:

- (UIImageView *)imageView {
    UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(5, 0, 34, 34)];
    imageView.layer.cornerRadius = CGRectGetWidth(profilePhotoImageView.frame) / 2.0f;
    imageView.layer.masksToBounds = YES;
    imageView.backgroundColor = [UIColor redColor];

    return imageView;
}

and then from the init method do

[self addSubView: [self imageView]];

But when I do myView.imageView.image = [UIImage someImage] the image doesn't show on the UIImageView.

What am I forgetting?

Can you show the rest of your implementation of the `imageView` getter method? — Gavin, Jan 16 '14 at 16:03
Refer to my answer for how you need to change your method to fix the problem, based on your updated question. — Gavin, Jan 16 '14 at 16:11
must check if ivar is previously initilized or not... if not just create like if(!_imageView){_imageView = [UIImageView alloc] init];} — Adnan Aftab, Jan 16 '14 at 16:22

score 1 · Accepted Answer · answered Jan 16 '14 at 16:09

1

Make sure that your imageView getter method is getting the UIImageView instance already stored in the instance variable _imageView. Otherwise each time you call the imageView method, you're creating a new instance of a UIImageView, so you're not going to be setting the image on the instance that actually got added to your view.

So, here's how your imageView method should look:

- (UIImageView *) imageView {
    UIImageView *imageView = _imageView;
    imageView.layer.cornerRadius = CGRectGetWidth(profilePhotoImageView.frame) / 2.0f;
    imageView.layer.masksToBounds = YES;
    imageView.backgroundColor = [UIColor redColor];

    return imageView;
}

answered Jan 16 '14 at 16:09

Gavin

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So the instance variable should have been already initialized? – Oscar Swanros Jan 16 '14 at 16:15
1

You could also move the code that initializes the `UIImageView` into your `imageView` getter method so it doesn't get initialized at all until it's needed. This would be lazy instantiation. – Gavin Jan 16 '14 at 16:21
1

It's important to remember, if you do go for lazy instantiation, that you only create a new `UIImageView` if it hasn't already been created. So you would do a check, like `if (!_imageView)` before creating a new one and setting up its parameters. – Gavin Jan 16 '14 at 16:31
Yep, that's the way I did it, and now everything is working and my class looks a lot cleaner :D – Oscar Swanros Jan 16 '14 at 17:06

score 0 · Answer 2 · answered Jan 16 '14 at 16:08

When you name your method imageView, it overrides the getter for your property. So every time you call it, you're calling the method and creating a new UIImageView.

IE,

myView.imageView

and

[myView imageView]

both call the method you defined, which returns a new UIImageView, not the one you created in init.

Getters and setters for UIView

2 Answers2