如何測試滾動視圖是否彈起？

Question

如何測試滾動視圖是否彈起？彈跳結束時是否有通知？

Answer 1

是的......檢查出UIScrollViewDelegate規範，實現包括以下兩個方法，並據此設置UIScrollView的委託：

// User stops dragging the table view. 

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView 
    willDecelerate:(BOOL)decelerate; 

// Control slows to a halt after the user drags it 

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView; 

你可能最感興趣的scrollViewDidEndDecelerating。這些也在UITableView中工作，這是我最初找到它們的地方（UITableView繼承自UIScrollView）。

Answer 2

這是我如何檢測如果滾動視圖水平反彈：

- (void)scrollViewDidScroll:(UIScrollView *)scrollView { 

    if (scrollView.contentOffset.x < 0) { 
    NSLog(@"bouncing left"); 
    } 

    if (scrollView.contentOffset.x > (scrollView.contentSize.width - scrollView.frame.size.width)) { 
    NSLog(@"bouncing right"); 
    } 
} 

Answer 3

輕微修訂Justin的方法，允許contentInset：

if(scrollView.contentOffset.x < -scrollView.contentInset.left) 
{ 
    NSLog(@"bounce left"); 
} 
if(scrollView.contentOffset.x > scrollView.contentSize.width - scrollView.frame.size.width + scrollView.contentInset.right) 
{ 
    NSLog(@"bounce right"); 
} 

Answer 4

對於那些你將能夠誰以在滾動視圖中向下「反彈」以更新視圖的內容。 （而該事件僅觸發一次。）

- (void)scrollViewDidEndDragging:(UIScrollView *)aScrollView 
        willDecelerate:(BOOL)decelerate{ 

    CGPoint offset = aScrollView.contentOffset; 
    CGRect bounds = aScrollView.bounds; 
    CGSize size = aScrollView.contentSize; 
    UIEdgeInsets inset = aScrollView.contentInset; 
    float y = offset.y + bounds.size.height - inset.bottom; 
    float h = size.height; 

    //Distance in points before update-event occur 
    float reload_distance = 50; 
    // 
    if(y > h + reload_distance) { 
     NSLog(@"load more rows"); 
    } 
} 

Answer 5

老問題，但我只是碰到了類似的問題，並想補充一點，這是一個好主意，還檢查滾動視圖內容大於滾動大視圖的框架：

+ (BOOL) isScrollViewBouncing:(UIScrollView *)scrollView 
{ 
    return scrollView.contentOffset.y > scrollView.contentSize.height - scrollView.frame.size.height 
      && scrollView.contentSize.height > scrollView.frame.size.height; 
} 

現在，這確保滾動視圖是大到足以在滾動彈跳的狀態，因此，如果滾動視圖小它並不總是爲true。

乾杯

Answer 6

使用Glavid的回答，我說反彈至底部還，並添加爲一個類別

#import "UIScrollView+Additions.h" 

@implementation UIScrollView (Additions) 

- (BOOL)isBouncing 
{ 
    BOOL isBouncingBottom = self.contentOffset.y >= self.contentSize.height - self.frame.size.height 
     && self.contentSize.height >= self.frame.size.height; 
    BOOL isBouncingTop = self.contentOffset.y <= 0; 

    BOOL isBouncing = isBouncingBottom || isBouncingTop; 
    return isBouncing; 
} 

@end 

Answer 7

我實現了擴展的UIScrollView來處理這種垂直和水平滾動。

Objective-C的

@interface UIScrollView (Bouncing) 

@property (nonatomic, readonly) BOOL isBouncing; 
@property (nonatomic, readonly) BOOL isBouncingTop; 
@property (nonatomic, readonly) BOOL isBouncingLeft; 
@property (nonatomic, readonly) BOOL isBouncingBottom; 
@property (nonatomic, readonly) BOOL isBouncingRight; 

@end 

@implementation UIScrollView (Bouncing) 

- (BOOL)isBouncing 
{ 
    return self.isBouncingTop || self.isBouncingLeft || self.isBouncingBottom || self.isBouncingRight; 
} 

- (BOOL)isBouncingTop 
{ 
    return self.contentOffset.y < - self.contentInset.top; 
} 

- (BOOL)isBouncingLeft 
{ 
    return self.contentOffset.x < - self.contentInset.left; 
} 

- (BOOL)isBouncingBottom 
{ 
    BOOL contentFillsScrollEdges = self.contentSize.height + self.contentInset.top + self.contentInset.bottom >= CGRectGetHeight(self.bounds); 
    return contentFillsScrollEdges && self.contentOffset.y > self.contentSize.height - CGRectGetHeight(self.bounds) + self.contentInset.bottom; 
} 

- (BOOL)isBouncingRight 
{ 
    BOOL contentFillsScrollEdges = self.contentSize.width + self.contentInset.left + self.contentInset.right >= CGRectGetWidth(self.bounds); 
    return contentFillsScrollEdges && self.contentOffset.x > self.contentSize.width - CGRectGetWidth(self.bounds) + self.contentInset.right; 
} 

@end 

斯威夫特3.0+

extension UIScrollView { 
    var isBouncing: Bool { 
    return isBouncingTop || isBouncingLeft || isBouncingBottom || isBouncingRight 
    } 
    var isBouncingTop: Bool { 
    return contentOffset.y < -contentInset.top 
    } 
    var isBouncingLeft: Bool { 
    return contentOffset.x < -contentInset.left 
    } 
    var isBouncingBottom: Bool { 
    let contentFillsScrollEdges = contentSize.height + contentInset.top + contentInset.bottom >= bounds.height 
    return contentFillsScrollEdges && contentOffset.y > contentSize.height - bounds.height + contentInset.bottom 
    } 
    var isBouncingRight: Bool { 
    let contentFillsScrollEdges = contentSize.width + contentInset.left + contentInset.right >= bounds.width 
    return contentFillsScrollEdges && contentOffset.x > contentSize.width - bounds.width + contentInset.right 
    } 
}