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iosuibuttontouchesmoveduicontrolevents

Draggable UIButton does not respond to UIControlEvents


When creating a Draggable UIButton, the dragging events work as they should, however, I am unable to figure out why the UIControlEvents do not respond when the button is simply pressed and not dragged.

Creating the Button

DraggableButton * camera = [DraggableButton buttonWithType:UIButtonTypeCustom];
[camera setFrame:CGRectMake(160,5,149,40)];
[camera setImage: [UIImage imageWithContentsOfFile:cameraMode] forState:UIControlStateNormal];
[camera setTitle: @"Camera" forState:UIControlStateNormal];  // never gets called.
[camera addTarget:self action:@selector(openCamera) forControlEvents:UIControlEventTouchUpInside];
[buttonView addSubview: camera];

Draggable Button

@interface DraggableButon : UIButton
{
@private float deltaX;
@private float deltaY;
    CGPoint startLocation;
    BOOL    dragging;
}
@end
@implementation DraggableButon
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
{
    [super touchesMoved:touches withEvent:event];

    if ( ! draggable ) return;

    dragging = YES;
    camera.enabled = NO;
    flash.enabled = NO;

    // Calculate offset
    CGPoint pt = [[[event allTouches] anyObject] locationInView:buttonView];
    deltaX = pt.x - startLocation.x;
    deltaY = pt.y - startLocation.y;

    float xx;
    if ( IPAD ) { xx = buttonView.center.x + deltaX; } else { xx = 160; }
    CGPoint newcenter = CGPointMake(xx, buttonView.center.y + deltaY);

    // Set new location
    buttonView.center = newcenter;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
    [super touchesBegan:touches withEvent:event];

    if ( ! draggable ) return;

    // Calculate and store offset, and pop view into front if needed
    CGPoint pt = [[[event allTouches] anyObject] locationInView:buttonView];
    startLocation = pt;
    [[self superview] bringSubviewToFront:buttonView];
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{        
    [super touchesEnded:touches withEvent:event];

    dragging = YES;
    if ( dragging )
    {
        camera.enabled = YES;
        flash.enabled = YES;

        //NSLog(@"touchesEnded: buttonView.frame.origin.x: %3.2f, buttonView.frame.origin.y: %3.2f",buttonView.frame.origin.x,buttonView.frame.origin.y);
        rectFromString = [NSString stringWithFormat:@"{{%3.2f,%3.2f},{320,50}}",buttonView.frame.origin.x,buttonView.frame.origin.y]; 
        NSMutableDictionary * dict = [[NSMutableDictionary alloc] initWithContentsOfFile: SETTINGS_FILE];
        [dict setObject:rectFromString forKey:@"kCGRectFromString"];
        [dict writeToFile: SETTINGS_FILE atomically:YES];
    }else{
        [self sendActionsForControlEvents:UIControlEventTouchUpInside];
    }
}
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event 
{    
    [super touchesCancelled:touches withEvent:event];
}
@end

Solution

  • the action is not called because you overwrite the touch events and you're not sending them further to super. You can add a new variable (let's call it dragged). Set this to NO at touchesBegan:, to YES at touchesMoved: and at touchesEnded:, if it's set to NO call [self sendActionsForControlEvents:UIControlEventTouchUpInside];

    @interface DraggableButon : UIButton
    {
    @private float deltaX;
    @private float deltaY;
        CGPoint startLocation;
        BOOL    dragging;
    }
    @end
    @implementation DraggableButon
    -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
    {
        dragging=NO;
    
        if ( ! draggable ) return;
    
        // Calculate and store offset, and pop view into front if needed
        CGPoint pt = [[[event allTouches] anyObject] locationInView:buttonView];
        startLocation = pt;
        [[self superview] bringSubviewToFront:buttonView];
    }
    -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
    {
        dragging=YES;
    
        if ( ! draggable ) return;
    
        camera.enabled = NO;
        flash.enabled = NO;
    
        // Calculate offset
        CGPoint pt = [[[event allTouches] anyObject] locationInView:buttonView];
        deltaX = pt.x - startLocation.x;
        deltaY = pt.y - startLocation.y;
    
        float xx;
        if ( IPAD ) { xx = buttonView.center.x + deltaX; } else { xx = 160; }
        CGPoint newcenter = CGPointMake(xx, buttonView.center.y + deltaY);
    
        // Set new location
        buttonView.center = newcenter;
    }
    -(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
    {        
        if(!dragging){  // or if(!dragging||!draggable)
            [self sendActionsForControlEvents:UIControlEventTouchUpInside];
            return;
        }
    
        camera.enabled = YES;
        flash.enabled = YES;
    
        //NSLog(@"touchesEnded: buttonView.frame.origin.x: %3.2f, buttonView.frame.origin.y: %3.2f",buttonView.frame.origin.x,buttonView.frame.origin.y);
        rectFromString = [NSString stringWithFormat:@"{{%3.2f,%3.2f},{320,50}}",buttonView.frame.origin.x,buttonView.frame.origin.y]; 
        NSMutableDictionary * dict = [[NSMutableDictionary alloc] initWithContentsOfFile: SETTINGS_FILE];
        [dict setObject:rectFromString forKey:@"kCGRectFromString"];
        [dict writeToFile: SETTINGS_FILE atomically:YES];
    }
    @end