点击每一个item后移动item改变item的位置。
实现这个功能有两种方案
1.第一种使用苹果给出的API直接调方法（IOS9以后）
2.第二种就是自己苦b的写移动前后的逻辑
通过查资料获得的两个方法代码大致如下
第一种直接调API
增加长按手势
//此处给其增加长按手势，用此手势触发cell移动效果
UILongPressGestureRecognizer *longGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handlelongGesture:)];
[_itemCollectionVIew addGestureRecognizer:longGesture];
手势调用的方法
//ios9以后的系统（ios9API）
-(void)IOS9_action:(UILongPressGestureRecognizer *)longGesture{
//判断手势状态
switch (longGesture.state) {
case UIGestureRecognizerStateBegan:{
//增加的抖动的动画
[self shake];
//判断手势落点位置是否在路径上
NSIndexPath *indexPath = [self.itemCollectionVIew indexPathForItemAtPoint:[longGesture locationInView:self.itemCollectionVIew]];
if (indexPath == nil) {
break;
}
//在路径上则开始移动该路径上的cell
[self.itemCollectionVIew beginInteractiveMovementForItemAtIndexPath:indexPath];
}
break;
case UIGestureRecognizerStateChanged:
//移动过程当中随时更新cell位置
[self.itemCollectionVIew updateInteractiveMovementTargetPosition:[longGesture locationInView:self.itemCollectionVIew]];
break;
case UIGestureRecognizerStateEnded:
//移动结束后关闭cell移动
[self.itemCollectionVIew endInteractiveMovement];
break;
default:
[self.itemCollectionVIew cancelInteractiveMovement];
break;
}
}
系统的回调方法
//是否允许移动item（ios9API）
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath{
//返回YES允许其item移动
return YES;
}
//item移动后改变的item的回调（ios9API）
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath {
//此处可以设置移动后的数据源的数组中的位置
//也可以不写，只是刷新后cell的状态不是你所想要的
}
调换数据源数组中的位置，可以参考下面方法
//self.dataArray是数据源数组
//SelectedListModel是cell的model
//将数据源数组按照改变的item的位置重新组装数组
-(void)compareMoveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath{
NSInteger location = 0;
NSInteger length = 0;
if (sourceIndexPath.item > destinationIndexPath.item) {
location = destinationIndexPath.item;
}else{
location = sourceIndexPath.item;
}
length = ABS(destinationIndexPath.item - sourceIndexPath.item)+1;
NSRange rang = NSMakeRange(location , length);
NSMutableIndexSet *set = [NSMutableIndexSet indexSet];
[set addIndexesInRange:rang];
NSMutableArray *array = [NSMutableArray arrayWithArray:[self.dataArray subarrayWithRange:rang]];
[self.dataArray removeObjectsAtIndexes:set];
if (location == sourceIndexPath.item) {
SelectedListModel *model1 = array.firstObject;
[array removeObjectAtIndex:0];
[array addObject:model1];
}else{
SelectedListModel *model1 = array.lastObject;
[array removeLastObject];
[array insertObject:model1 atIndex:0];
}
[self.dataArray insertObjects:array atIndexes:set];
}
第二种是为了适配iOS9以前的系统
用到的属性
/**之前选中cell的NSIndexPath*/
@property (nonatomic, strong) NSIndexPath *oldIndexPath;
/**单元格的截图*/
@property (nonatomic, strong) UIView *snapshotView;
/**之前选中cell的NSIndexPath*/
@property (nonatomic, strong) NSIndexPath *moveIndexPath;
手势实现的方法
//ios9以前的系统
-(void)action:(UILongPressGestureRecognizer *)longPress{
switch (longPress.state) {
case UIGestureRecognizerStateBegan:
{ // 手势开始
//判断手势落点位置是否在row上
NSIndexPath *indexPath = [self.itemCollectionVIew indexPathForItemAtPoint:[longPress locationInView:self.itemCollectionVIew]];
self.oldIndexPath = indexPath;
if (indexPath == nil) {
break;
}
UICollectionViewCell *cell = [self.itemCollectionVIew cellForItemAtIndexPath:indexPath];
// 使用系统的截图功能,得到cell的截图视图
UIView *snapshotView = [cell snapshotViewAfterScreenUpdates:NO];
snapshotView.layer.cornerRadius = 3;
snapshotView.layer.masksToBounds = YES;
snapshotView.frame = cell.frame;
[self.itemCollectionVIew addSubview:self.snapshotView = snapshotView];
// 截图后隐藏当前cell
cell.hidden = YES;
CGPoint currentPoint = [longPress locationInView:self.itemCollectionVIew];
[UIView animateWithDuration:0.25 animations:^{
snapshotView.transform = CGAffineTransformMakeScale(1.05, 1.05);
snapshotView.center = currentPoint;
}];
}
break;
case UIGestureRecognizerStateChanged:
{ // 手势改变
//当前手指位置 截图视图位置随着手指移动而移动
CGPoint currentPoint = [longPress locationInView:self.itemCollectionVIew];
self.snapshotView.center = currentPoint;
// 计算截图视图和哪个可见cell相交
for (UICollectionViewCell *cell in self.itemCollectionVIew.visibleCells) {
// 当前隐藏的cell就不需要交换了,直接continue
if ([self.itemCollectionVIew indexPathForCell:cell] == self.oldIndexPath) {
continue;
}
// 计算中心距
CGFloat space = sqrtf(pow(self.snapshotView.center.x - cell.center.x, 2) + powf(self.snapshotView.center.y - cell.center.y, 2));
if (space <= self.snapshotView.bounds.size.width / 2) {
self.moveIndexPath = [self.itemCollectionVIew indexPathForCell:cell];
//移动 会调用willMoveToIndexPath方法更新数据源
[self.itemCollectionVIew moveItemAtIndexPath:self.oldIndexPath toIndexPath:self.moveIndexPath];
//上面提到的方法，将数据源数组按照改变的item的位置重新组装数组
[self compareMoveItemAtIndexPath:_oldIndexPath toIndexPath:_moveIndexPath];
//设置移动后的起始indexPath
self.oldIndexPath = self.moveIndexPath;
break;
}
}
}
break;
default:
{ // 手势结束和其他状态
UICollectionViewCell *cell = [self.itemCollectionVIew cellForItemAtIndexPath:self.oldIndexPath];
// 结束动画过程中停止交互,防止出问题
self.itemCollectionVIew.userInteractionEnabled = NO;
// 给截图视图一个动画移动到隐藏cell的新位置
[UIView animateWithDuration:0.25 animations:^{
self.snapshotView.center = cell.center;
self.snapshotView.transform = CGAffineTransformMakeScale(1.0, 1.0);
} completion:^(BOOL finished) {
// 移除截图视图,显示隐藏的cell并开始交互
[self.snapshotView removeFromSuperview];
cell.hidden = NO;
self.itemCollectionVIew.userInteractionEnabled = YES;
}];
}
break;
}
}
根据需要调用
- (void)handlelongGesture:(UILongPressGestureRecognizer *)longGesture {
//判断是否是ios以前的系统
if ([[[UIDevice currentDevice] systemVersion] floatValue] < 9.0){
[self action:longGesture];
}else{
[self IOS9_action:longGesture];
}
}
注释写的很清楚，理解应该不是很难。。。
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