Question

Here is the situation. I have a view controller titled “MyViewController.” Within this view controller I have a text editing feature that uses subclassed buttons. The name of the UIButton Subclass is “ColorSwatch”

I have setup delegate/protocol methods in the “ColorSwatch.h” subclass as follow.

//  ColorSwatch.h

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

@protocol ColorSwatchDelegate <NSObject>
- (void)fontColor:(UIColor *)color;
@end

@interface ColorSwatch : UIButton {
id <ColorSwatchDelegate> colorSwatchDelegate;
    CAGradientLayer *gradient;
    UIView *currentView;
    UIColor *fontColor;
}

@property (nonatomic, retain) id <ColorSwatchDelegate> colorSwatchDelegate;
@property (nonatomic, retain) CAGradientLayer *gradient; 
@property (nonatomic, retain) UIView *currentView;
@property (nonatomic, retain) UIColor *fontColor;

@end

Now in my “ColorSwatch.m” I have:

//  ColorSwatch.m

#import "ColorSwatch.h"
#import <QuartzCore/QuartzCore.h>
#import "MyViewController.h"

@implementation ColorSwatch

@synthesize gradient; 
@synthesize currentView;
@synthesize colorSwatchDelegate;
@synthesize fontColor;

-(void)setupView{
    "Makes the subclassed buttons pretty"
}

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

    }

    return self;
}

-(id)initWithCoder:(NSCoder *)aDecoder{
    if((self = [super initWithCoder:aDecoder])){
        [self setupView];
        MyViewController *mvc = [[MyViewController alloc] initWithNibName:
                                           @"MyViewController" bundle:nil];
        self.colorSwatchDelegate = mvc;
    }

    return self;
}


-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    [self magnify:view];
    fontColor = view.backgroundColor;
    [self.colorSwatchDelegate fontColor:fontColor];
}

- (void)magnify:(UIView *)view
{

}

- (void)dealloc
{
    [currentView release];
    [gradient release];
    [fontColor release];

    [super dealloc];
}

@end

In the “MyViewController.h” I have:

//  MyViewController.h

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


@interface MyViewController : UIViewController <ColorSwatchDelegate> {    

UITextField *photoLabelTextField;

}

@property (nonatomic, retain) IBOutlet UITextField *photoLabelTextField;

@end

In the “MyViewController.m” I have:

- (void)fontColor:(UIColor *)color
{
    NSLog(@"Selected Font Color");
    [self.photoLabelTextField setTextColor:color];
}

Now the delegate method sort of works, meaning when I tap on a color button the

NSLog(@"Selected Font Color");

message gets fired. But the problem is that I cannot change the

[self.photoLabelTextField setTextColor:color];

property. I have tried numerous ways of changing the property, the only thing that I can do is send NSLogs, anything I try to change a property in the “MyViewController” Class nothing happens.

If anyone could please help me out, I would appreciate it.

Thank you

Answer 1

The problem is that the ColorSwatch is sending delegate messages to a dangling instance of MyViewController that it incorrectly allocated in it’s initWithCoder: method.

UIControls shouldn’t allocate ViewControllers to be their delegates… it goes the other way around.

Delete these lines…

// in ColorSwatch.m initWithCoder:
MyViewController *mvc = [[MyViewController alloc] initWithNibName:
                                           @"MyViewController" bundle:nil];
self.colorSwatchDelegate = mvc;

Then, in MyViewController.m …

- (void)viewDidLoad {

    ColorSwatch *colorSwatchButton = [[ColorSwatch alloc] buttonWithType:UIButtonTypeCustom];

    // or place a ColorSwatch in the xib, on MyViewController's view... But not before you
    // you delete lines from initWithCoder, otherwise it's infinite circular allocation

    colorSwatchButton.frame = CGRectMake(/* ... */);
    colorSwatchButton addTarget:self action:@selector(csButtonPressed:) forControlEvent: UIControlEventTouchUpInside];
    // and so on...
    // now the important part:
    colorSwatchButton.colorSwatchDelegate = self;

    // see - the ViewController is in charge of allocation, sets itself up as the delegate
    [self.view addSubview:colorSwatchButton];
}

Instead of building the button in code, you can use IB.

Step 1: make the delegate an outlet…

@property (nonatomic, retain) IBOutlet id <ColorSwatchDelegate> colorSwatchDelegate;

Step 2: draw the buttons in IB, and set their class to ColorSwatch.
Then you can skip the code I wrote in viewDidLoad.

Step 3: The newly placed button should now present an outlet in IB. You can drag from that to the MyViewController as you normally do.