CODEWITHSUNDEEP
objective-ciosuibutton
Zhen
Zhen

Reputation: 12431

objective C: Buttons created from subclass of UIButton class not working

I am creating a subclass of UIButton in order to create my own customized buttons. My code as follows:

//interface file (subclass of uIButton
@interface UICustomButton : UIButton 
{
    Answer *answer;
    NSString *btnType;
}

@property (nonatomic, retain) Answer *answer;
@property (nonatomic, assign) NSString *btnType;

- (id)initWithAnswer:(Answer *)ans andButtonType:(NSString *)type andFrame:(CGRect)frame; 
- (void)buttonPressed;

@end


//Implementation file (.m)
@implementation UICustomButton
@synthesize answer,btnType;

- (id)initWithAnswer:(Answer *)ans andButtonType:(NSString *)type andFrame:(CGRect)frame; 
{
    self = [super initWithFrame:frame];
    if (self) 
    {
        self = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
        self.backgroundColor = [UIColor colorWithHexString:@"#E2E4E7"];

    }

    [self addTarget:self action:@selector(buttonPressed) forControlEvents:UIControlStateNormal];

    self.answer = ans;
    self.btnType = type;

    return self;
}

I am facing some issues in getting the above code to work. I have 2 problems

1) The buttons are not responding to the selector method "buttonPressed"

2) I am hitting a runtime error for the lines 'self.answer = ans' and 'self.btnType = type' Stack trace as follows:

-[UIButton setAnswer:]: unrecognized selector sent to instance 0x614ebc0
2011-06-23 00:55:27.038 onethingaday[97355:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIButton setAnswer:]: unrecognized selector sent to instance 0x614ebc0'

What am I doing wrong here?

Upvotes: 14

Views: 33338

Answers (5)

Eiko
Eiko

Reputation: 25632

Edit

This answer reaches back several years, and things have changed - as Apple docs now explicitly mention subclassing and gives some hints.

So the following answer might be irrelevant or wrong for current development and might be ignored if you're interested in the current state of the art.

UIButton is not meant to be subclassed.

You are better off making a category and defining a factory method that delivers your needed button (with proper call to buttonWithType:). initWithFrame: is not the correct way to initialize a button anyway.

Upvotes: 1

kanstraktar
kanstraktar

Reputation: 5357

If you want to get notifications when the user is interacting with your buttons, just sublcass UIButton and implement these methods:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"touchesBegan");
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"touchesEnded");
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"touchesCancelled");
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"touchesMoved");
}

No init method required.

Upvotes: 1

Sishu
Sishu

Reputation: 1558

//
//  BtnClass.m

#import "BtnClass.h"

@implementation BtnClass

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


    }
    return self;
}

//added custum properities to button
-(id)initWithCoder:(NSCoder *)aDecoder
{
    NSLog(@"initWithCoder");
    self = [super initWithCoder: aDecoder];
    if (self) {
        // Initialization code

        _numberOfItems=[[UILabel alloc]initWithFrame:CGRectMake(40, 8, 160, 30)];
        _numberOfItems.textAlignment=NSTextAlignmentLeft;
        _numberOfItems.font = [UIFont boldSystemFontOfSize:18.0];
        _numberOfItems.textColor = [UIColor darkGrayColor];
        [self addSubview:_numberOfItems];
        _leftImage=[[UIImageView alloc]initWithFrame:CGRectMake(10, 10, 25, 25)];
        [self addSubview:_leftImage];
        _rightImage=[[UIImageView alloc]initWithFrame:CGRectMake(280, 10, 15, 15)];
        [self addSubview:_rightImage];
        [self setImage:[UIImage imageNamed:@"list-bg2-1.png"] forState:UIControlStateNormal];
        [_rightImage setImage:[UIImage imageNamed:@"carat.png"]];
        self.backgroundColor=[UIColor blackColor];


        if(self.tag==1)
        {
            [_leftImage setImage:[UIImage imageNamed:@"notes-icon.png"]];

        }
        if(self.tag==2)
        {
            [_leftImage setImage:[UIImage imageNamed:@"photos-icon.png"]];

        }
        if(self.tag==3)
        {
            [_leftImage setImage:[UIImage imageNamed:@"videos-icon.png"]];

        }


    }
    return self;
}

//selected method of uibutton
-(void)setSelected:(BOOL)selected
{

    [super setSelected:selected];


    if(selected)
    {
        [self setImage:nil forState:UIControlStateNormal];
        _numberOfItems.textColor = [UIColor whiteColor];

        [_rightImage setImage:[UIImage imageNamed:@"carat-open.png"]];

        if(self.tag==1)
        {
            [_leftImage setImage:[UIImage imageNamed:@"white-notes-icon.png"]];
        }
        else if(self.tag==2)
        {

            [_leftImage setImage:[UIImage imageNamed:@"white-photo-icon.png"]];

        }
        else
        {
            [_leftImage setImage:[UIImage imageNamed:@"white-video-icon.png"]];

        }

    }
    else{

        _numberOfItems.textColor = [UIColor darkGrayColor];

        if(self.tag==1)
        {
            [_leftImage setImage:[UIImage imageNamed:@"notes-icon.png"]];

        }
        if(self.tag==2)
        {
            [_leftImage setImage:[UIImage imageNamed:@"photos-icon.png"]];

        }
        if(self.tag==3)
        {
            [_leftImage setImage:[UIImage imageNamed:@"videos-icon.png"]];

        }

        [self setImage:[UIImage imageNamed:@"list-bg2-1.png"] forState:UIControlStateNormal];

        [_rightImage setImage:[UIImage imageNamed:@"carat.png"]];

    }
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

@end

Upvotes: 0

Jonny
Jonny

Reputation: 16298

Not sure this was in the docs before, but anyway these are the current notes on + (id)buttonWithType:(UIButtonType)buttonType...

To me it looks like subclassing is OK as long as you use init instead of buttonWithType. I have yet to try it myself however.

Discussion This method is a convenience constructor for creating button objects with specific configurations. It you subclass UIButton, this method does not return an instance of your subclass. If you want to create an instance of a specific subclass, you must alloc/init the button directly.

When creating a custom button—that is a button with the type UIButtonTypeCustom—the frame of the button is set to (0, 0, 0, 0) initially. Before adding the button to your interface, you should update the frame to a more appropriate value.

Upvotes: 10

Felipe Sabino
Felipe Sabino

Reputation: 18215

This is happening because you are creating a UIButton type object and not a UICustomButton type inside the init method when you do 

self = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];

Try replacing your init method for

- (id)initWithAnswer:(Answer *)ans andButtonType:(NSString *)type andFrame:(CGRect)frame; 
{
    self = [self initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
    if (self) 
    {
        self.backgroundColor = [UIColor colorWithHexString:@"#E2E4E7"];

        [self addTarget:self action:@selector(buttonPressed) forControlEvents:UIControlEventTouchUpInside];

        self.answer = ans;
        self.btnType = type;
    }

    return self;
}

This will cause self to be a UICustomButton type object.

Also, you are using a wrong type for the UIControlState parameter when you add the target to your button using the addTarget:action:forControlEvents: method

You should use value among the ones bellow:

UIControlEventTouchDown
UIControlEventTouchDownRepeat
UIControlEventTouchDragInside
UIControlEventTouchDragOutside
UIControlEventTouchDragEnter
UIControlEventTouchDragExit
UIControlEventTouchUpInside
UIControlEventTouchUpOutside
UIControlEventTouchCancel

EDIT: Notes on UIButton subclassing

Many references on the web say you should NOT subclass the UIButton class, but not only anybody said why but what also deeply annoyed me was that the UIButton Class Reference does not say anything about it at all.

If you take UIWebView Class Reference for example, it explicitly states that you should not subclass UIWebView

Subclassing Notes The UIWebView class should not be subclassed.

the big deal with UIButton is that it inherits from UIControl and a good and simple explanation is on the UIControl Class Reference itself

Subclassing Notes You may want to extend a UIControl subclass for either of two reasons:

  • To observe or modify the dispatch of action messages to targets for particular events
  • To provide custom tracking behavior (for example, to change the highlight appearance)

So, this means that you CAN subclass a UIButton, but you should be careful on what you are doing. Just subclass it to change its behavior and not its appearance. To modify a UIButton appearance you should use the interface methods provided for that, such as:

setTitle:forState:
setBackgroundImage:forState:
setImage:forState:

References worth reading

Source: my post here

Upvotes: 30

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