期望效果
JXMovableCellTableView.gif
1.长按即可触发移动cell，操作逻辑简单；
2.移动cell时越靠近屏幕边缘，速度越快；
3.被移动cell的样式可以自定义；
github地址
JXMovableCellTableView,如果你喜欢，不妨给颗星吧_~
调研
如果只是实现移动UITableViewCell，系统自带的API即可搞定。
调用下面的方法[tableView setEditing:YES animated:YES];即可进入编辑模式。然后实现下面的方法即可开启移动cell。
//默认编辑模式下，每个cell左边有个红色的删除按钮，设置为None即可去掉
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
return UITableViewCellEditingStyleNone;
}
//是否允许indexPath的cell移动
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath
{
//更新数据源
}
用系统的方法有几个缺点：
1.需要用一个开关去控制编辑状态，不方便；
2.移动cell的时候cell右边有个指示图标，看着不爽；
3.被移动cell的样式不能自己定制。
综上所述，需要自己去写效果了。
实现原理
大概原理：为UITableView添加一个长按手势，然后给选中的cell截图；让截图随着手势移动，同时记录选中的indexPath，方便位置互换。
1.添加长按手势
- (void)jx_addGesture
{
_gesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(jx_processGesture:)];
_gesture.minimumPressDuration = _gestureMinimumPressDuration;
[self addGestureRecognizer:_gesture];
}
2.处理手势开始，需要通过dataSource方法获取数据源
- (void)jx_gestureBegan:(UILongPressGestureRecognizer *)gesture
{
CGPoint point = [gesture locationInView:gesture.view];
NSIndexPath *selectedIndexPath = [self indexPathForRowAtPoint:point];
if (!selectedIndexPath) {
return;
}
if (self.delegate && [self.delegate respondsToSelector:@selector(tableView:willMoveCellAtIndexPath:)]) {
[self.delegate tableView:self willMoveCellAtIndexPath:selectedIndexPath];
}
if (_canEdgeScroll) {
//开启边缘滚动
[self jx_startEdgeScroll];
}
//每次移动开始获取一次数据源
if (self.dataSource && [self.dataSource respondsToSelector:@selector(dataSourceArrayInTableView:)]) {
_tempDataSource = [self.dataSource dataSourceArrayInTableView:self].mutableCopy;
}
_selectedIndexPath = selectedIndexPath;
UITableViewCell *cell = [self cellForRowAtIndexPath:selectedIndexPath];
_tempView = [self jx_snapshotViewWithInputView:cell];
if (_drawMovalbeCellBlock) {
//将_tempView通过block让使用者自定义
_drawMovalbeCellBlock(_tempView);
}else {
//配置默认样式
_tempView.layer.shadowColor = [UIColor grayColor].CGColor;
_tempView.layer.masksToBounds = NO;
_tempView.layer.cornerRadius = 0;
_tempView.layer.shadowOffset = CGSizeMake(-5, 0);
_tempView.layer.shadowOpacity = 0.4;
_tempView.layer.shadowRadius = 5;
}
_tempView.frame = cell.frame;
[self addSubview:_tempView];
//隐藏cell
cell.hidden = YES;
[UIView animateWithDuration:kJXMovableCellAnimationTime animations:^{
_tempView.center = CGPointMake(_tempView.center.x, point.y);
}];
}
3.处理手势变化，移动成功之后用delegate告诉使用者
- (void)jx_gestureChanged:(UILongPressGestureRecognizer *)gesture
{
CGPoint point = [gesture locationInView:gesture.view];
NSIndexPath *currentIndexPath = [self indexPathForRowAtPoint:point];
if (currentIndexPath && ![_selectedIndexPath isEqual:currentIndexPath]) {
//交换数据源和cell
[self jx_updateDataSourceAndCellFromIndexPath:_selectedIndexPath toIndexPath:currentIndexPath];
if (self.delegate && [self.delegate respondsToSelector:@selector(tableView:didMoveCellFromIndexPath:toIndexPath:)]) {
[self.delegate tableView:self didMoveCellFromIndexPath:_selectedIndexPath toIndexPath:currentIndexPath];
}
_selectedIndexPath = currentIndexPath;
}
//让截图跟随手势
_tempView.center = CGPointMake(_tempView.center.x, point.y);
}
交换数据源和cell
- (void)jx_updateDataSourceAndCellFromIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
if ([self numberOfSections] == 1) {
//只有一组
[_tempDataSource exchangeObjectAtIndex:fromIndexPath.row withObjectAtIndex:toIndexPath.row];
//交换cell
[self moveRowAtIndexPath:fromIndexPath toIndexPath:toIndexPath];
}else {
//有多组
id fromData = _tempDataSource[fromIndexPath.section][fromIndexPath.row];
id toData = _tempDataSource[toIndexPath.section][toIndexPath.row];
NSMutableArray *fromArray = [_tempDataSource[fromIndexPath.section] mutableCopy];
NSMutableArray *toArray = [_tempDataSource[toIndexPath.section] mutableCopy];
[fromArray replaceObjectAtIndex:fromIndexPath.row withObject:toData];
[toArray replaceObjectAtIndex:toIndexPath.row withObject:fromData];
[_tempDataSource replaceObjectAtIndex:fromIndexPath.section withObject:fromArray];
[_tempDataSource replaceObjectAtIndex:toIndexPath.section withObject:toArray];
//交换cell
[self beginUpdates];
[self moveRowAtIndexPath:fromIndexPath toIndexPath:toIndexPath];
[self moveRowAtIndexPath:toIndexPath toIndexPath:fromIndexPath];
[self endUpdates];
}
}
4.处理手势结束或取消，结束之后通过dataSource代理返回交换后的数据源。
- (void)jx_gestureEndedOrCancelled:(UILongPressGestureRecognizer *)gesture
{
if (_canEdgeScroll) {
[self jx_stopEdgeScroll];
}
//返回交换后的数据源
if (self.dataSource && [self.dataSource respondsToSelector:@selector(tableView:newDataSourceArrayAfterMove:)]) {
[self.dataSource tableView:self newDataSourceArrayAfterMove:_tempDataSource.copy];
}
if (self.delegate && [self.delegate respondsToSelector:@selector(tableView:endMoveCellAtIndexPath:)]) {
[self.delegate tableView:self endMoveCellAtIndexPath:_selectedIndexPath];
}
UITableViewCell *cell = [self cellForRowAtIndexPath:_selectedIndexPath];
[UIView animateWithDuration:kJXMovableCellAnimationTime animations:^{
_tempView.frame = cell.frame;
} completion:^(BOOL finished) {
cell.hidden = NO;
[_tempView removeFromSuperview];
_tempView = nil;
}];
}
5.开启边缘滚动
用CADisplayLink实现，1/60秒刷新一次，和屏幕刷新频率一样。
- (void)jx_startEdgeScroll
{
_edgeScrollTimer = [CADisplayLink displayLinkWithTarget:self selector:@selector(jx_processEdgeScroll)];
[_edgeScrollTimer addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
}
6.处理边缘滚动
- (void)jx_processEdgeScroll
{
[self jx_gestureChanged:_gesture];
CGFloat minOffsetY = self.contentOffset.y + _edgeScrollRange;
CGFloat maxOffsetY = self.contentOffset.y + self.bounds.size.height - _edgeScrollRange;
CGPoint touchPoint = _tempView.center;
//处理上下达到极限之后不再滚动tableView，其中处理了滚动到最边缘的时候，当前处于edgeScrollRange内，但是tableView还未显示完，需要显示完tableView才停止滚动
if (touchPoint.y < _edgeScrollRange) {
if (self.contentOffset.y <= 0) {
return;
}else {
if (self.contentOffset.y - 1 < 0) {
return;
}
[self setContentOffset:CGPointMake(self.contentOffset.x, self.contentOffset.y - 1) animated:NO];
_tempView.center = CGPointMake(_tempView.center.x, _tempView.center.y - 1);
}
}
if (touchPoint.y > self.contentSize.height - _edgeScrollRange) {
if (self.contentOffset.y >= self.contentSize.height - self.bounds.size.height) {
return;
}else {
if (self.contentOffset.y + 1 > self.contentSize.height - self.bounds.size.height) {
return;
}
[self setContentOffset:CGPointMake(self.contentOffset.x, self.contentOffset.y + 1) animated:NO];
_tempView.center = CGPointMake(_tempView.center.x, _tempView.center.y + 1);
}
}
//处理滚动
CGFloat maxMoveDistance = 20;
if (touchPoint.y < minOffsetY) {
//cell在往上移动, moveDistance越大移动越快
CGFloat moveDistance = (minOffsetY - touchPoint.y)/_edgeScrollRange*maxMoveDistance;
[self setContentOffset:CGPointMake(self.contentOffset.x, self.contentOffset.y - moveDistance) animated:NO];
_tempView.center = CGPointMake(_tempView.center.x, _tempView.center.y - moveDistance);
}else if (touchPoint.y > maxOffsetY) {
//cell在往下移动, moveDistance越大移动越快
CGFloat moveDistance = (touchPoint.y - maxOffsetY)/_edgeScrollRange*maxMoveDistance;
[self setContentOffset:CGPointMake(self.contentOffset.x, self.contentOffset.y + moveDistance) animated:NO];
_tempView.center = CGPointMake(_tempView.center.x, _tempView.center.y + moveDistance);
}
}
使用
直接继承JXMovableCellTableView就可以使用了，然后通过公开属性进行自定义：
/**
* 长按手势最小触发时间，默认1.0，最小0.2
*/
@property (nonatomic, assign) CGFloat gestureMinimumPressDuration;
/**
* 自定义可移动cell的截图样式
*/
@property (nonatomic, copy) void(^drawMovalbeCellBlock)(UIView *movableCell);
/**
* 是否允许拖动到屏幕边缘后，开启边缘滚动，默认YES
*/
@property (nonatomic, assign) BOOL canEdgeScroll;
/**
* 边缘滚动触发范围，默认150，越靠近边缘速度越快
*/
@property (nonatomic, assign) CGFloat edgeScrollRange;
总结
通过截图大法实现以假乱真，自由移动截图产生的"cell"；交换的时候，首先要交换数据源，再交换cell；处理边缘滚动的时候，需要小心各种边界条件。
既然UITableViewCell可以自由移动了，那么UICollectionViewCell同理也可以实现。下篇文章就讲可移动UICollectionViewCell的实现。
