Objective-C-Scrollview事件

Question

I found some answer that quite solve my questions, but seems that I'm missing some steps. I'm just trying to intercept the "ViewDidBlablabla" events of a ScrollView, so I created a custom UIScrollView class.

MyScrollView.m

#import "MyScrollView.h"

@implementation MyScrollView

- (id)initWithFrame:(CGRect)frame{
    NSLog(@"initWithFrame");
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

-(void)scrollViewWillBeginDragging:(UIScrollView*)scrollView{
    NSLog(@"scrollViewWillBeginDragging");
    //scrollView.contentOffset
}

-(void)scrollViewDidScroll:(UIScrollView*)scrollView{
    NSLog(@"scrollViewDidScroll");
}

-(void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
    NSLog(@"scrollViewDidEndScrollingAnimation");
}

@end

MyScrollView.h

#import <UIKit/UIKit.h>

@interface MyScrollView : UIScrollView <UIScrollViewDelegate>

@end

When I alloc my custom Scroll View I do get the console message "initWithFrame", but there's no way to get to the other events. What am I missing?

If you need some other pieces of code feel free to ask, but since I get to my custom "initWithFrame" method, I suppose that the error should be here.

Answer 1

Try setting your view as the delegate of itself:

if (self) {
    // Initialization code
    self.delegate = self;
}

Technically, you do not need to inherit UIScrollView to respond to scrolling events: it is sufficient to set the delegate to an implementation of <UIScrollViewDelegate> .

Also, the scrollViewDidEndScrollingAnimation: method has been gone for about two years , so it is not going to be called on modern iOS installations.