Wednesday, June 5, 2013

UIScrollView touchesShouldBegin example in Objective C (iOS).

UIScrollView touchesShouldBegin

Overridden by subclasses to customize the default behavior when a finger touches down in displayed content.

- (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view

A set of UITouch instances that represent the touches for the starting phase of the event represented by event.
An object representing the event to which the touch objects in touches belong.
The subview in the content where the touch-down gesture occurred.

Return Value of [UIScrollView touchesShouldBegin]
Return NO if you don’t want the scroll view to send event messages to view. If you want view to receive those messages, return YES (the default).

Discussion of [UIScrollView touchesShouldBegin]
The default behavior of UIScrollView is to invoke the UIResponder event-handling methods of the target subview that the touches occur in.

UIScrollView touchesShouldBegin example.
- (BOOL) touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view {
    if ([touches count] == 2) {
        return YES;
    else {
        return NO;

Example of [UIScrollView touchesShouldBegin].
- (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view
id  element;
NSEnumerator *setEnum =   [touches objectEnumerator];

while ((element = [setEnum nextObject]) != nil)
    NSLog(@"element:%@", element);   

return [super touchesShouldBegin:touches withEvent:event inContentView:view];

UIScrollView touchesShouldBegin example.
 The default behavior of UIScrollView is to invoke
 the UIResponder event-handling methods of the target subview that the touches occur in.
- (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view
BOOL ret;
ret = [super touchesShouldBegin:touches withEvent:event inContentView:view];

NSLog(@"SwTextView touchesShouldBegin,return YES");
NSLog(@"SwTextView touchesShouldBegin,return NO");

return ret;

End of UIScrollView touchesShouldBegin example article.