iOS-TableView拖動Cell更換次序

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效果：

長按某個Cell，Cell會有一個明顯的彈起放大效果。這時候，你可以通過拖動cell和其他Cell更換順序。

 

實現的原理：

1，浮層

長按後，UITableViewCell上會出現一個浮層，同時UITableViewCell隱藏。並且浮層可拖動。（對UITableViewCell產生一個快照）

 1 #pragma mark - Helper methods 2  3 /** @brief Returns a customized snapshot of a given view. */ 4 - (UIView *)customSnapshoFromView:(UIView *)inputView { 5     UIView* snapshot = nil; 6      7     if ([[[UIDevice currentDevice] systemVersion] doubleValue] < 7.0) { 8         //ios7.0 以下通過形式儲存快照 9         snapshot = [self customSnapShortFromViewEx:inputView];10     }else{11         //ios7.0 系統的快照方法12         snapshot = [inputView snapshotViewAfterScreenUpdates:YES];13     }14     15     snapshot.layer.masksToBounds = NO;16     snapshot.layer.cornerRadius = 0.0;17     snapshot.layer.shadowOffset = CGSizeMake(-5.0, 0.0);18     snapshot.layer.shadowRadius = 5.0;19     snapshot.layer.shadowOpacity = 0.4;20     21     return snapshot;22 }23 24 - (UIView *)customSnapShortFromViewEx:(UIView *)inputView25 {26     CGSize inSize = inputView.bounds.size;27     // 下面方法，第一個參數表示地區大小。第二個參數表示是否是非透明的。如果需要顯示半透明效果，需要傳NO，否則傳YES。第三個參數就是螢幕密度了28     UIGraphicsBeginImageContextWithOptions(inSize, NO, [UIScreen mainScreen].scale);29     [inputView.layer renderInContext:UIGraphicsGetCurrentContext()];30     UIImage *image= UIGraphicsGetImageFromCurrentImageContext();31     UIGraphicsEndImageContext();32     UIImageView* snapshot = [[UIImageView alloc] initWithImage:image];33     34     return snapshot;35 }

2，更換某對UITableViewCell的位置

?

1 2 3 4

// ... update data source. [_items exchangeObjectAtIndex:indexPath.row withObjectAtIndex:sourceIndexPath.row];              // ... move the rows. [_tableView moveRowAtIndexPath:sourceIndexPath toIndexPath:indexPath];

datasource裡面的data的位置替換，同時將tableView的Cell位置替換。

 1 - (void)longPressGestureRecognized:(id)sender { 2      3     UILongPressGestureRecognizer *longPress = (UILongPressGestureRecognizer *)sender; 4     UIGestureRecognizerState state = longPress.state; 5      6     CGPoint location = [longPress locationInView:_tableView]; 7     NSIndexPath *indexPath = [_tableView indexPathForRowAtPoint:location]; 8      9     static UIView       *snapshot = nil;        ///< A snapshot of the row user is moving.10     static NSIndexPath  *sourceIndexPath = nil; ///< Initial index path, where gesture begins.11     12     switch (state) {13         case UIGestureRecognizerStateBegan: {14             if (indexPath) {15                 sourceIndexPath = indexPath;16                 17                 UITableViewCell *cell = [_tableView cellForRowAtIndexPath:indexPath];18                 19                 // Take a snapshot of the selected row using helper method.20                 snapshot = [self customSnapshoFromView:cell];21                 22                 // Add the snapshot as subview, centered at cell‘s center...23                 __block CGPoint center = cell.center;24                 snapshot.center = center;25                 snapshot.alpha = 0.0;26                 [_tableView addSubview:snapshot];27                 [UIView animateWithDuration:0.25 animations:^{28                     29                     // Offset for gesture location.30                     center.y = location.y;31                     snapshot.center = center;32                     snapshot.transform = CGAffineTransformMakeScale(1.05, 1.05);33                     snapshot.alpha = 0.98;34                     35                     cell.alpha = 0.0f;36                 } completion:^(BOOL finished) {37                     cell.hidden = YES;38                 }];39             }40             break;41         }42             43         case UIGestureRecognizerStateChanged: {44             CGPoint center = snapshot.center;45             center.y = location.y;46             snapshot.center = center;47             48             // Is destination valid and is it different from source?49             if (indexPath && ![indexPath isEqual:sourceIndexPath]) {50                 51                 // ... update data source.52                 [_items exchangeObjectAtIndex:indexPath.row withObjectAtIndex:sourceIndexPath.row];53                 54                 // ... move the rows.55                 [_tableView moveRowAtIndexPath:sourceIndexPath toIndexPath:indexPath];56                 57                 // ... and update source so it is in sync with UI changes.58                 sourceIndexPath = indexPath;59             }60             break;61         }62             63         default: {64             // Clean up.65             UITableViewCell *cell = [_tableView cellForRowAtIndexPath:sourceIndexPath];66             [UIView animateWithDuration:0.25 animations:^{67                 68                 snapshot.center = cell.center;69                 snapshot.transform = CGAffineTransformIdentity;70                 snapshot.alpha = 0.0;71                 72                 cell.alpha = 1.0f;73             } completion:^(BOOL finished) {74                 cell.hidden = NO;75                 [snapshot removeFromSuperview];76                 snapshot = nil;77                 78             }];79             sourceIndexPath = nil;80             break;81         }82     }83 }

3,  ......似乎沒有其他了吧？

你看，是不是很簡單呢！只需要上面幾行代碼，你就可以實現一個稍微有點好看的UITableViewCell變換位置的效果了。

下載Demo