iOS - Create UIView subclass for rounded rectangle

问题

I'm trying to create & use a very simple UIView subclass for a rectangle with rounded corners. I've created a new class as follows :

RoundedRect.h

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface RoundedRect : UIView
@end

RoundedRect.m

#import "RoundedRect.h"

@implementation RoundedRect

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        [[self layer] setCornerRadius:10.0f];
        [[self layer] setMasksToBounds:YES];
    }
    return self;
}
@end

I'm using iOS 5.1 with storyboards and have set the custom class property in the IB inspector window to 'RoundedRect', but when I run the app the rectangle still has square corners. Have I missed something obvious?

Thanks Jonathan

回答1:

The initWithFrame method is not called when the view is instantiated from a XIB file. Instead, the initWithCoder: initializer is called, so you need to perform the same initialization in this method.

回答2:

In iOS 5 and up, there is absolutely no need to subclass - you can do it all from Interface Builder.

Select the UIView you want to modify.
Go to the Identity Inspector.
In "User Defined & Runtime Attributes", add "layer.cornerRadius" in Key Path, Type should be "Number" and whatever setting you require.
Also add 'layer.masksToBounds' as Boolean.
Done! With no subclassing, and all in IB.

回答3:

The other guys have already answered the question but I would refactor it like this to enable use in nibs and in code

#import "RoundedRect.h"

@implementation RoundedRect

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

- (id)initWithCoder:(NSCoder *)aDecoder;
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self commonInit];
    }
    return self;
}

- (void)commonInit;
{
    CALayer *layer = self.layer;
    layer.cornerRadius  = 10.0f;
    layer.masksToBounds = YES;
}

@end