Notes

Cocoa and iOS Notes

Gesture recognizers:

After load, add the recognizer:

UITapGestureRecognizer *recognizer;
recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapRecognized:)];
[self.scrollView addGestureRecognizer:recognizer];
[recognizer release];

For the handler:

-(void)tapRecognized:(UITapGestureRecognizer *)sender{
	// ...
}

Note that swipe gestures need to be registered separately:

// right
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeRecognized:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];

// left
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeRecognized:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];

To detect the direction (or the view touched, etc), the handler can inspect sender: 

-(void)swipeRecognized:(UISwipeGestureRecognizer *)sender{
	NSLog(@"got swipe:%d", sender.direction);
}

Using Categories to Extend Stuff

In UIView+mycat.h:

@interface UIView(mycat)
-(void)myMethod;
@end

In UIView+mycat.m:

#import "UIView+mycat.h"

@implementation UIView(mycat)

- (void)myMethod {
.. do some stuff
}

@end

AppDelegate shortcut

#define AppDelegate (YourAppDelegate *)[[UIApplication sharedApplication] delegate]