SubClassing UILabel | 易学教程

问题

I read in this same site how to inset and UILabel (subclass UILabel and override the required methods). Before adding it to my app I decided to test it out in a standalone test app. Code is shown below.

Here's MyUILabel.h

#import <UIKit/UIKit.h>

@interface MyUILabel : UILabel

@end

Here's MyUILabel.m

#import "MyUILabel.h"
#import <QuartzCore/QuartzCore.h>

@implementation MyUILabel

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

// for border and rounding
-(void) drawRect:(CGRect)rect
{
    self.layer.cornerRadius = 4.0;
    self.layer.borderWidth = 2;

    [super drawRect:rect];
}

// for inset
-(void) drawTextInRect:(CGRect)rect
{
    UIEdgeInsets insets = {0, 5, 0, 5};

    [super drawTextInRect: UIEdgeInsetsInsetRect(rect, insets)];
}

Here's my ViewController.h

#import <UIKit/UIKit.h>
#import "MyUILabel.h"


@interface ViewController : UIViewController
{
    MyUILabel   *myDisplay;
}

@property (strong, nonatomic) IBOutlet MyUILabel *myDisplay;

@end

Here's ViewController.m:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize myDisplay;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    myDisplay.text = @"Hello World!";
}

- (void)viewDidUnload
{
    [self setMyDisplay:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

@end

None of the methods in MyUILabel.m (that Im overriding) get called.

Insights into why are greatly appreciated.

Regards,

Ramon.

回答1:

Ok. I did some further digging and in Xcode there is a field visible when looking at the nib file. Its the 'Identity Inspector' (3rd icon from left). This needed to be changed from UILabel to MyUILabel.

Now it works!

来源：https://stackoverflow.com/questions/10004466/subclassing-uilabel

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uilabel

subclass