最近因需要實(shí)現(xiàn)一個(gè)標(biāo)簽類的 demo, 需要支持拖拽重排, 首先想到的便是 collectionView, 并且很快就在 API 文檔中找到了類似的接口:
- (BOOL)beginInteractiveMovementForItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0);
- (void)updateInteractiveMovementTargetPosition:(CGPoint)targetPosition NS_AVAILABLE_IOS(9_0);
- (void)endInteractiveMovement NS_AVAILABLE_IOS(9_0);
- (void)cancelInteractiveMovement NS_AVAILABLE_IOS(9_0);
用系統(tǒng)提供的這幾個(gè)接口很快便能實(shí)現(xiàn)我們的需求, 代碼見 gitbub地址.
但是你有沒有發(fā)現(xiàn)上面的方法后面跟著的NS_AVAILABLE_IOS(9_0), iOS9才開始支持, 這就尷尬了.
那iOS9之前怎么手動(dòng)實(shí)現(xiàn)這個(gè)需求呢, 于是邊分析邊開始列出實(shí)現(xiàn)步驟:
- 長(zhǎng)按 cell 進(jìn)入拖拽模式
- 隱藏當(dāng)前 cell, 并添加一個(gè)當(dāng)前 cell 的截圖到 collectionView 上
- 隨手勢(shì)移動(dòng)截圖, 當(dāng)截圖的center 進(jìn)入到另一個(gè) cell2 的范圍內(nèi)的時(shí)候, 將隱藏的 cell 移動(dòng)到cell2的位置, 并移動(dòng) cell2及cell2之后的 cell
- 若繼續(xù)移動(dòng), 則執(zhí)行(3)
- 若松開手指結(jié)束移動(dòng), 則移除掉截圖, 并顯示之前隱藏的 cell
過(guò)程理順了, 那么接下來(lái)便是代碼的實(shí)現(xiàn)了.
1. 長(zhǎng)按 cell 進(jìn)入拖拽模式
我這里直接給 collectionView添加了一個(gè)長(zhǎng)按手勢(shì)
UILongPressGestureRecognizer *longG = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPress:)];
longG.minimumPressDuration = 0.2f;
[self.collectionView addGestureRecognizer:longG];
- (void)longPress:(UILongPressGestureRecognizer *)lpGesture
{
switch(lpGesture.state) {
case UIGestureRecognizerStateBegan:
{
[self collectionViewCellDidBeginChange:lpGesture];
break;
}
case UIGestureRecognizerStateChanged:
{
[self collectionViewCellDidChange:lpGesture];
break;
}
case UIGestureRecognizerStateEnded:
{
[self collectionViewCellDidEndChange:lpGesture];
break;
}
default:
if (AVAILABLE_IOS_9_0)
{
[self.collectionView cancelInteractiveMovement];
}
break;
}
}
2. 隱藏當(dāng)前 cell, 并添加一個(gè)當(dāng)前 cell 的截圖到 collectionView 上
- (void)collectionViewCellDidBeginChange:(UILongPressGestureRecognizer *)lpGesture
{
self.beginIndexPath = [self.collectionView indexPathForItemAtPoint:[lpGesture locationInView:self.collectionView]];
self.beginCell = (CollectionViewCell *)[self.collectionView cellForItemAtIndexPath:self.beginIndexPath];
if (AVAILABLE_IOS_9_0)
{
[self.collectionView beginInteractiveMovementForItemAtIndexPath:self.beginIndexPath];
}
else
{
// 截圖 并隱藏原 cell
self.tempView = [self.beginCell snapshotViewAfterScreenUpdates:YES];
self.tempView.frame = self.beginCell.frame;
[self.collectionView addSubview:self.tempView];
self.beginPoint = [lpGesture locationInView:self.collectionView];
self.beginCell.hidden = YES;
}
}
3. 移動(dòng)截圖
- (void)collectionViewCellDidChange:(UILongPressGestureRecognizer *)lpGesture
{
CGPoint targetPosion = [lpGesture locationInView:lpGesture.view];
if (AVAILABLE_IOS_9_0)
{
[self.collectionView updateInteractiveMovementTargetPosition:targetPosion];
}
else
{
CGFloat tranX = [lpGesture locationOfTouch:0 inView:self.collectionView].x - self.beginPoint.x;
CGFloat tranY = [lpGesture locationOfTouch:0 inView:self.collectionView].y - self.beginPoint.y;
// 設(shè)置截圖視圖位置
self.tempView.center = CGPointApplyAffineTransform(self.tempView.center, CGAffineTransformMakeTranslation(tranX, tranY));
self.beginPoint = [lpGesture locationOfTouch:0 inView:_collectionView];
// 計(jì)算截圖視圖和哪個(gè)cell相交
for (UICollectionViewCell *cell in [_collectionView visibleCells])
{
//跳過(guò)隱藏的cell
if ([_collectionView indexPathForCell:cell] == self.beginIndexPath)
{
continue;
}
//計(jì)算中心距
CGFloat space = sqrtf(pow(self.tempView.center.x - cell.center.x, 2) + powf(self.tempView.center.y - cell.center.y, 2));
//如果相交一半且兩個(gè)視圖Y的絕對(duì)值小于高度的一半就移動(dòng)
if (space <= self.tempView.bounds.size.width * 0.5 && (fabs(self.tempView.center.y - cell.center.y) <= self.tempView.bounds.size.height * 0.5))
{
NSIndexPath *nextIndexPath = [_collectionView indexPathForCell:cell];
[self updateDataWithSourceIndexPath:self.beginIndexPath toIndexPath:nextIndexPath];
[_collectionView moveItemAtIndexPath:self.beginIndexPath toIndexPath:nextIndexPath];
//設(shè)置移動(dòng)后的起始indexPath
self.beginIndexPath = nextIndexPath;
break;
}
}
}
}
數(shù)據(jù)源的改動(dòng)
- (void)updateDataWithSourceIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath
{
if (sourceIndexPath.section == destinationIndexPath.section) // 同一個(gè) section 間移動(dòng)
{
if (destinationIndexPath.item > sourceIndexPath.item) {
for (NSUInteger i = sourceIndexPath.item; i < destinationIndexPath.item ; i ++) {
[self.dataArray[sourceIndexPath.section] exchangeObjectAtIndex:i withObjectAtIndex:i + 1];
}
}else{
for (NSUInteger i = sourceIndexPath.item; i > destinationIndexPath.item ; i --) {
[self.dataArray[sourceIndexPath.section] exchangeObjectAtIndex:i withObjectAtIndex:i - 1];
}
}
}
else // 不同 section 之間移動(dòng) , 刪除 sourceData, 插入到 destinationData
{
NSMutableArray *sourceArr = self.dataArray[sourceIndexPath.section];
NSMutableArray *destinationArr = self.dataArray[destinationIndexPath.section];
id obj = [sourceArr objectAtIndex:sourceIndexPath.row];
[sourceArr removeObjectAtIndex:sourceIndexPath.row];
[destinationArr insertObject:obj atIndex:destinationIndexPath.row];
}
}
4. 若繼續(xù)移動(dòng), 則執(zhí)行(3)
5. 若松開手指結(jié)束移動(dòng), 則移除掉截圖, 并顯示之前隱藏的 cell
- (void)collectionViewCellDidEndChange:(UILongPressGestureRecognizer *)lpGesture
{
if (AVAILABLE_IOS_9_0)
{
[self.collectionView endInteractiveMovement];
}
else
{
[UIView animateWithDuration:0.25 animations:^{
self.tempView.center = self.beginCell.center;
}completion:^(BOOL finished) {
[self.tempView removeFromSuperview];
self.beginCell.hidden = NO;
}];
}
}
好了, 到此就完成了 iOS9以下的適配, 實(shí)現(xiàn)起來(lái)也不是很復(fù)雜, 主要的是實(shí)現(xiàn)之前把思路理順, 那實(shí)現(xiàn)起來(lái)就不難了.
詳細(xì)的代碼見gitbub地址.如果有收獲,歡迎 star!
