效果：
长按某个Cell，Cell会有一个明显的弹起放大效果。这时候，你可以通过拖动cell和其他Cell更换顺序。
实现的原理：
1，浮层
长按后，UITableViewCell上会出现一个浮层，同时UITableViewCell隐藏。并且浮层可拖动。（对UITableViewCell生成一个快照）
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 以下通过截图形式保存快照
9 snapshot = [self customSnapShortFromViewEx:inputView];
10 }else{
11 //ios7.0 系统的快照方法
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 *)inputView
25 {
26 CGSize inSize = inputView.bounds.size;
27 // 下面方法，第一个参数表示区域大小。第二个参数表示是否是非透明的。如果需要显示半透明效果，需要传NO，否则传YES。第三个参数就是屏幕密度了
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，更换某对UITableViewCell的位置
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1 2 3 4 |
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datasource里面的data的位置替换，同时将tableView的Cell位置替换。
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, ......似乎没有其他了吧？
你看，是不是很简单呢！只需要上面几行代码，你就可以实现一个稍微有点好看的UITableViewCell变换位置的效果了。
时间： 2024-10-15 00:41:28