Detect touch globally

Question

I trying to figure out how to solve this (fairly) simple problem but I failing miserably, so I really need your advice.

My application consists of a uitabbar with se

Answer 1

If you must include the code detection in your uiimageview subclass then I would tell the appdelegate that a touch was received and where. The app delegate could then either tell all your uiimageviews or tell the viewcontroller which would tell it's uiimageviews.

untested code:

appDelegate = (myAppDelegate *)[[UIApplication sharedApplication] delegate];
[appDelegate touchedAt:(int)xPos yPos:(int)yPos];

Answer 2

To catch all touch events globally I ended up subclassing UIWindow as follows:

//  CustomUIWindow.h
#import <UIKit/UIKit.h>

#define kTouchPhaseBeganCustomNotification @"TouchPhaseBeganCustomNotification"

@interface CustomUIWindow : UIWindow
@property (nonatomic, assign) BOOL enableTouchNotifications;
@end

//  CustomUIWindow.m
#import "CustomUIWindow.h"

@implementation CustomUIWindow

@synthesize enableTouchNotifications = enableTouchNotifications_;

- (void)sendEvent:(UIEvent *)event
{
    [super sendEvent:event];  // Apple says you must always call this!

    if (self.enableTouchNotification) {
        [[NSNotificationCenter defaultCenter] postNotificationName:kTouchPhaseBeganCustomNotification object:event];
    }
}@end

Then whenever I need to start listening to all touches globally I do the following:

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(stopThumbnailWobble:)
                                             name:kTouchPhaseBeganCustomNotification
                                           object:nil];

((CustomUIWindow *)self.window).enableTouchNotification = YES;   

In stopThumbnailWobble I remove the observer and process the UITouch event to decide whether to remove the thumb or not:

- (void)stopThumbnailWobble:(NSNotification *)event
{    
    [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                    name:kTouchPhaseBeganCustomNotification 
                                                  object:nil];
    ((CustomUIWindow *)self.window).enableTouchNotification = NO;

    UIEvent *touchEvent = event.object;
    // process touchEvent and decide what to do
    ...

Hope this helps others.