UIScrollview with UIButtons - how to recreate springboard?

Patrick picture Patrick · Mar 16, 2009 · Viewed 35.2k times · Source

I'm trying to create a springboard-like interface within my app. I'm trying to use UIButtons added to a UIScrollView. The problem I'm running in to is with the buttons not passing any touches to the UIScrollView - if I try to flick/slide and happen to press on the button it doesn't register for the UIScrollView, but if I flick the space between buttons it will work. The buttons do click/work if I touch them.

Is there a property or setting that forces the button to send the touch events up to its parent (superview)? Do the buttons need to be added to something else before being added the UIScrollView?

Here is my code:

//init scrolling area
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 480, 480)];
scrollView.contentSize = CGSizeMake(480, 1000);
scrollView.bounces = NO;
scrollView.delaysContentTouches = NO;

//create background image
UIImageView *rowsBackground = [[UIImageView alloc] initWithImage:[self scaleAndRotateImage:[UIImage imageNamed:@"mylongbackground.png"]]];
rowsBackground.userInteractionEnabled = YES;

//create button
UIButton *btn = [[UIButton buttonWithType:UIButtonTypeCustom] retain];
btn.frame = CGRectMake(100, 850, 150, 150);
btn.bounds = CGRectMake(0, 0, 150.0, 150.0);
[btn setImage:[self scaleAndRotateImage:[UIImage imageNamed:@"basicbutton.png"]] forState:UIControlStateNormal];
[btn addTarget:self action:@selector(buttonClick) forControlEvents:UIControlEventTouchUpInside];

//add "stuff" to scrolling area
[scrollView addSubview:rowsBackground];
[scrollView addSubview:btn];

//add scrolling area to cocos2d
//this is just a UIWindow
[[[Director sharedDirector] openGLView] addSubview:scrollView];

//mem-mgmt
[rowsBackground release];
[btn release];
[scrollView release];

Answer

Roman Kishchenko picture Roman Kishchenko · Aug 4, 2010

Solution that worked for me included:

  1. Setting canCancelContentTouches in UIScrollView to YES.
  2. Extending UIScrollView to override touchesShouldCancelInContentView:(UIView *)view to return YES when view is a UIButton.

According to documentation touchesShouldCancelInContentView returns "YES to cancel further touch messages to view, NO to have view continue to receive those messages. The default returned value is YES if view is not a UIControl object; otherwise, it returns NO."

Since UIButton is a UIControl the extension is necessary to get canCancelContentTouches to take effect which enables scrolling.