CODEWITHSUNDEEP
objective-cuiview
Groxx
Groxx

Reputation: 2499

Subclassed UIView with custom init - is this sane?

I've been casting around looking for best-practices and whatnot for creating custom, reusable view components. So far, it seems like a custom UIView subclass is the way to go.

In this case, all I need is a fixed-size view with easy access to a label, and a convenience initializer would be great. I could tag the label and use a constant, but it seems unnecessary given this (boilerplate like UIKit importing removed) (with ARC):

// .h file
@interface MyView : UIView
@property (nonatomic, weak) IBOutlet UILabel *label;
+ (id)withText:(NSString *)text;
@end

// .m file
@implementation MyView
+ (id)withText:(NSString *)text {
    MyView *view = [[[NSBundle mainBundle] loadNibNamed:NSStringFromClass([self class])
                                                  owner:nil
                                                options:nil] objectAtIndex:0];
    view.label.text = text;
    return view;
}
@end

(edit: changed to class method. my concerns are still unchanged, though it's a bit less dubious overall)

My MyView.xib file's only top-level element (a UIView) has a custom class set to MyView, and the outlet is hooked up to the FileOwner.

And... this works. Perfectly. It renders correctly everywhere I'm using it, no exceptions, no clipping, no funny business at all that I can see.

So far. I'm more than a little concerned that:

  1. I haven't seen this technique anywhere yet. Of course, I've only been looking for a relatively short time (a couple hours, passively).
  2. I'm not doing any of the recommended overriding of initWithFrame: / Coder: etc.
  3. I'm only using this in an extremely-limited realm right now, so it is nowhere near well tested for situations like the view going out of view, the drawing performance is unknown, I haven't checked thoroughly for memory leaks, etc.
  4. I'm almost certain I'm missing something. Most likely I'll find it shortly while using it more, but I may not find all of them.

Does someone with more UIView experience than I have mind lending their brain for a bit? Is this a good idea? A horrifying "omg wtf are you thinking" idea? Are there surprises waiting for me? Is there something I should read for how to create simple custom views like this?

Upvotes: 0

Views: 261

Answers (2)

Wolf McNally
Wolf McNally

Reputation: 3657

In general, this technique should be fine. Since you're calling a class method as a "convenience initializer," self refers to the class object and will not change, so it's fine to refer to it there. This is not anything like swizzling self in an initializer, which is trickier, but which can be done correctly.

In the case above, only the initWithCoder: initializer will be called, as you're loading the view from a Nib.

Upvotes: 0

zoul
zoul

Reputation: 104065

You should read the Apple docs on initializers, and there’s also Mike Ash’s posts about them. Initializers are not hard, but there are some subtle issues that could bite you, as you could find out with your current code, as already mentioned in the comments.

Upvotes: 1

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