UIScrollView disable vertical bounce only at bottom

Question

I\'ve been searching for a way to disable vertical bounce for a UIScrollView but only at bottom. I still need to have the bounce at the top.

Couldn\'t find anything.

Answer 1

Based on 0x7fffffff's answer I've created a class:

VerticalBounceControl.h

#import 

@interface VerticalBounceControl : NSObject

@property (nonatomic, assign) BOOL bounce;

- (id) initWithScrollView:(UIScrollView*)scrollView bounceAtTop:(BOOL)bounceAtTop bounceAtBottom:(BOOL)bounceAtBottom;

@end

VerticalBounceControl.m

#import "VerticalBounceControl.h"

@interface VerticalBounceControl ()
@property (nonatomic, retain) UIScrollView* scrollView;
@property (nonatomic, assign) BOOL bounceAtTop;
@property (nonatomic, assign) BOOL bounceAtBottom;
@end

@implementation VerticalBounceControl

- (id) initWithScrollView:(UIScrollView*)scrollView bounceAtTop:(BOOL)bounceAtTop bounceAtBottom:(BOOL)bounceAtBottom {
    self = [super init];
    if(self) {
        self.bounce = YES;
        self.scrollView = scrollView;
        self.bounceAtTop = bounceAtTop;
        self.bounceAtBottom = bounceAtBottom;
        [self.scrollView addObserver:self forKeyPath:@"contentOffset" options:NSKeyValueObservingOptionNew context:NULL];
    }
    return self;
}

- (void) dealloc {
    [self.scrollView removeObserver:self forKeyPath:@"contentOffset"];
    self.scrollView = nil;
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([keyPath isEqualToString:@"contentOffset"]) {
        if (self.bounce && ((self.scrollView.contentOffset.y<=0 && self.bounceAtTop) || (self.scrollView.contentOffset.y>=self.scrollView.contentSize.height-1 && self.bounceAtBottom))) {
            self.scrollView.bounces = YES;
        } else {
            self.scrollView.bounces = NO;
        }
    }
}

@end

that can be used without the caller being a delegate of UIScrollView like this:

VerticalBounceControl* bounceControl = [[VerticalBounceControl alloc] initWithScrollView:anyScrollView bounceAtTop:YES bounceAtBottom:NO];

This way you can have this bounce behavior for UIScrollViews that you don't want to alter their delegate (like UIWebView's one).

Again, thanks go @0x7fffffff for the solution!