以下是我前面的问题moveRowAtIndexPath-在区段之间移动单元格
我已经能够做一个传统的moveRowAtIndexPath来在部分之间移动单元格，即：将标记从Sales移动到Marketing。
然而，现在我想更进一步，在表视图上添加长按手势，并允许我从简单地在单元格上使用长按移动单元格。
作为参考，我的表是在不同Departments工作的Employees的列表；其中模型是自定义的，但只包含简单的名称字符串。
我的排是这样的；
-(NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
return [_objects count];
}
-(NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
Department *department = [_objects objectAtIndex:section];
return [department.employees count];
}
我当前的moveRowAtIndexPath是：
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
if (fromIndexPath != toIndexPath ) {
Department *departmentFrom = [_objects objectAtIndex:fromIndexPath.section];
Department *departmentTo = [_objects objectAtIndex:toIndexPath.section];
Employee *employee = [departmentFrom.employees objectAtIndex:fromIndexPath.row];
[departmentFrom.employees removeObjectAtIndex:fromIndexPath.row];
[departmentTo.employees insertObject:employee atIndex:toIndexPath.row];
[tableView reloadData];
}
}
因此，现在我在查看DidLoad时将长按添加到表中，ala；
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressGestureRecognized:)];
[self.tableView addGestureRecognizer:longPress];
然后终于有了我的长按代码本身；
- (IBAction)longPressGestureRecognized:(id)sender {
UILongPressGestureRecognizer *longPress = (UILongPressGestureRecognizer *)sender;
UIGestureRecognizerState state = longPress.state;
CGPoint location = [longPress locationInView:self.tableView];
NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:location];
static UIView *snapshot = nil; ///< A snapshot of the row user is moving.
static NSIndexPath *sourceIndexPath = nil; ///< Initial index path, where gesture begins.
switch (state) {
case UIGestureRecognizerStateBegan: {
if (indexPath) {
sourceIndexPath = indexPath;
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
// Take a snapshot of the selected row using helper method.
snapshot = [self customSnapshoFromView:cell];
// Add the snapshot as subview, centered at cell's center...
__block CGPoint center = cell.center;
snapshot.center = center;
snapshot.alpha = 0.0;
[self.tableView addSubview:snapshot];
[UIView animateWithDuration:0.25 animations:^{
// Offset for gesture location.
center.y = location.y;
snapshot.center = center;
snapshot.transform = CGAffineTransformMakeScale(1.05, 1.05);
snapshot.alpha = 0.98;
cell.alpha = 0.0;
} completion:^(BOOL finished) {
cell.hidden = YES;
}];
}
break;
}
case UIGestureRecognizerStateChanged: {
CGPoint center = snapshot.center;
center.y = location.y;
snapshot.center = center;
// Is destination valid and is it different from source?
if (indexPath && ![indexPath isEqual:sourceIndexPath]) {
// ... update data source.
// ... move the rows.
[self.tableView moveRowAtIndexPath:sourceIndexPath toIndexPath:indexPath];
// ... and update source so it is in sync with UI changes.
sourceIndexPath = indexPath;
}
break;
}
default: {
// Clean up.
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:sourceIndexPath];
cell.hidden = NO;
cell.alpha = 0.0;
[UIView animateWithDuration:0.25 animations:^{
snapshot.center = cell.center;
snapshot.transform = CGAffineTransformIdentity;
snapshot.alpha = 0.0;
cell.alpha = 1.0;
} completion:^(BOOL finished) {
sourceIndexPath = nil;
[snapshot removeFromSuperview];
snapshot = nil;
}];
break;
}
}
}
#pragma mark - Helper methods
/** @brief Returns a customized snapshot of a given view. */
- (UIView *)customSnapshoFromView:(UIView *)inputView {
// Make an image from the input view.
UIGraphicsBeginImageContextWithOptions(inputView.bounds.size, NO, 0);
[inputView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Create an image view.
UIView *snapshot = [[UIImageView alloc] initWithImage:image];
snapshot.layer.masksToBounds = NO;
snapshot.layer.cornerRadius = 0.0;
snapshot.layer.shadowOffset = CGSizeMake(-5.0, 0.0);
snapshot.layer.shadowRadius = 5.0;
snapshot.layer.shadowOpacity = 0.4;
return snapshot;
}
不幸的是，这在UIGestureRecognizerStateChanged中崩溃了，它试图移动细胞；这与移动后/移动前数组不一致有关。
此外，我不确定我做得是否正确；这种模式能在基于部门和员工的列表中工作吗？
无论如何，我在这里的问题是：如何将长按手势添加到由部分组成的表视图单元格中，或者。。我想用长按把汤姆从销售部门调到市场部。
给定上面的代码，这可能吗？
编辑；
我得到的崩溃是：
"NSInternalConferenceException"，原因："无效更新：无效节0中的行数。包含在更新后的现有节（3）必须等于更新（3）之前该节中包含的行，加或减从该部分插入或删除的行数（插入0，0已删除），加上或减去移入或移出的行数该节（0已移入，1已移出）。'***第一次投掷呼叫st
进一步更新：@2016年1月14日
事实证明，公认的答案仍然让我崩溃。原因是它假设发生了交换；但事实并非如此。
我通过重复我的代码来删除一个项目，然后将其重新添加回中，从而解决了这个问题
这是张贴在下面；
case UIGestureRecognizerStateChanged: {
CGPoint center = snapshot.center;
center.y = location.y;
center.x = location.x;
snapshot.center = center;
// Is destination valid and is it different from source?
if (indexPath && ![indexPath isEqual:sourceIndexPath])
{
Department *departmentFrom = [_objects objectAtIndex:sourceIndexPath.section];
Department *departmentTo = [_objects objectAtIndex:indexPath.section];
[self.tableView beginUpdates];
Employee *employee = [departmentFrom.employees objectAtIndex:sourceIndexPath.row];
[departmentFrom.employees removeObjectAtIndex:sourceIndexPath.row];
[departmentTo.employees insertObject:employee atIndex:indexPath.row];
[self.tableView moveRowAtIndexPath:sourceIndexPath toIndexPath:indexPath];
[self.tableView endUpdates];
// ... and update source so it is in sync with UI changes.
sourceIndexPath = indexPath;
}
break;
}
我能看到的唯一问题是tableView:moveRowAtIndexPath和此代码都在重复相同的代码。
但我可以稍后清理。
感谢
case UIGestureRecognizerStateChanged: {
CGPoint center = snapshot.center;
center.y = location.y;
center.x = location.x;
snapshot.center = center;
// Is destination valid and is it different from source?
if (indexPath && ![indexPath isEqual:sourceIndexPath]) {
[self.stackTableView beginUpdates];
// ... update data source.
NSLog(@"exchanging");
[self.stackObjectArray exchangeObjectAtIndex:indexPath.section withObjectAtIndex:sourceIndexPath.section];
// ... move the rows.
NSLog(@"moving the rows");
[self.stackTableView moveRowAtIndexPath:indexPath toIndexPath:sourceIndexPath];
[self.stackTableView moveRowAtIndexPath:sourceIndexPath toIndexPath:indexPath];
NSLog(@"ending updates");
[self.stackTableView endUpdates];
// ... and update source so it is in sync with UI changes.
sourceIndexPath = indexPath;
}
break;
}
好了！
您需要做的是防止表视图立即更新，并使用beginUpdate和endUpdates同时执行所有更改。这样你就不会出现这样的错误。您还需要同时交换行，而不仅仅是移动它们。
我知道在Ray Wenderlich的例子中，他只提到了移动的行，所以给你！
http://www.raywenderlich.com/63089/cookbook-moving-table-view-cells-with-a-long-press-gesture