一.介紹
iOS9提供API實現單元格排序功能，使用UICollectionView及其代理方法。iOS9之后有自帶方法可以實現該效果，只需添加長按手勢，實現手勢方法和調用iOS9的API交換數據，iOS9之前需要自己寫方法實現這效果，除了要添加長按手勢，這里還需要利用截圖替換原理，手動計算移動位置來處理視圖交換和數據交換。
二.方法和步驟
1.創建工程項目和視圖控制器,如下圖
2.聲明對象和設置代理和數據源代理
@interface ViewController ()<UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout> @property (nonatomic, strong) NSMutableArray *dataArr;@property (nonatomic, strong) UICollectionView *collectionView;/**之前選中cell的NSIndexPath*/@property (nonatomic, strong) NSIndexPath *oldIndexPath;/**單元格的截圖*/@property (nonatomic, strong) UIView *snapshotView;/**之前選中cell的NSIndexPath*/@property (nonatomic, strong) NSIndexPath *moveIndexPath; @end
3.初始化UICollectionView,并添加長按手勢,在viewDidLoad中初始化
CGFloat SCREEN_WIDTH = self.view.frame.size.width; UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init]; flowLayout.itemSize = CGSizeMake((SCREEN_WIDTH-40.0)/3, (SCREEN_WIDTH-40.0)/3); UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 50.0, SCREEN_WIDTH, (SCREEN_WIDTH-40.0)/3+20.0) collectionViewLayout:flowLayout]; collectionView.dataSource = self; collectionView.delegate = self; collectionView.backgroundColor = [UIColor whiteColor]; [collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"uicollectionviewcell"]; [self.view addSubview:self.collectionView = collectionView]; // 添加長按手勢 UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handlelongGesture:)]; [collectionView addGestureRecognizer:longPress];
4.實例化數據源,(50個隨機顏色,透明度0.8),在viewDidLoad中初始化
self.dataArr = [[NSMutableArray alloc] init];for (NSInteger index = 0; index < 50; index ++) { CGFloat hue = (arc4random()%256/256.0); //0.0 到 1.0 CGFloat saturation = (arc4random()%128/256.0)+0.5; //0.5 到 1.0 CGFloat brightness = (arc4random()%128/256.0)+0.5; //0.5 到 1.0 UIColor *color = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:0.5]; [self.dataArr addObject:color]; }5.實現UICollectionView的UICollectionViewDataSource的兩個必須實現的方法
#pragma mark - UICollectionViewDataSource- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ return self.dataArr.count;} - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"uicollectionviewcell" forIndexPath:indexPath]; cell.backgroundColor = self.dataArr[indexPath.row]; return cell;}6.重點來了,實現長按手勢方法
#pragma mark - 長按手勢- (void)handlelongGesture:(UILongPressGestureRecognizer *)longPress{ if ([[[UIDevice currentDevice] systemVersion] floatValue] < 9.0) { [self action:longPress]; } else { [self iOS9_Action:longPress]; }}7.iOS9之后的實現
#pragma mark - iOS9 之后的方法- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath{ // 返回YES允許row移動 return YES;} - (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath{ //取出移動row數據 id color = self.dataArr[sourceIndexPath.row]; //從數據源中移除該數據 [self.dataArr removeObject:color]; //將數據插入到數據源中的目標位置 [self.dataArr insertObject:color atIndex:destinationIndexPath.row];} - (void)iOS9_Action:(UILongPressGestureRecognizer *)longPress{ switch (longPress.state) { case UIGestureRecognizerStateBegan: { //手勢開始 //判斷手勢落點位置是否在row上 NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:[longPress locationInView:self.collectionView]]; if (indexPath == nil) { break; } UICollectionViewCell *cell = [self.collectionView cellForItemAtIndexPath:indexPath]; [self.view bringSubviewToFront:cell]; //iOS9方法 移動cell [self.collectionView beginInteractiveMovementForItemAtIndexPath:indexPath]; } break; case UIGestureRecognizerStateChanged: { // 手勢改變 // iOS9方法 移動過程中隨時更新cell位置 [self.collectionView updateInteractiveMovementTargetPosition:[longPress locationInView:self.collectionView]]; } break; case UIGestureRecognizerStateEnded: { // 手勢結束 // iOS9方法 移動結束后關閉cell移動 [self.collectionView endInteractiveMovement]; } break; default: //手勢其他狀態 [self.collectionView cancelInteractiveMovement]; break; }}8.iOS9之前的實現
#pragma mark - iOS9 之前的方法- (void)action:(UILongPressGestureRecognizer *)longPress{ switch (longPress.state) { case UIGestureRecognizerStateBegan: { // 手勢開始 //判斷手勢落點位置是否在row上 NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:[longPress locationInView:self.collectionView]]; self.oldIndexPath = indexPath; if (indexPath == nil) { break; } UICollectionViewCell *cell = [self.collectionView cellForItemAtIndexPath:indexPath]; // 使用系統的截圖功能,得到cell的截圖視圖 UIView *snapshotView = [cell snapshotViewAfterScreenUpdates:NO]; snapshotView.frame = cell.frame; [self.view addSubview:self.snapshotView = snapshotView]; // 截圖后隱藏當前cell cell.hidden = YES; CGPoint currentPoint = [longPress locationInView:self.collectionView]; [UIView animateWithDuration:0.25 animations:^{ snapshotView.transform = CGAffineTransformMakeScale(1.05, 1.05); snapshotView.center = currentPoint; }]; } break; case UIGestureRecognizerStateChanged: { // 手勢改變 //當前手指位置 截圖視圖位置隨著手指移動而移動 CGPoint currentPoint = [longPress locationInView:self.collectionView]; self.snapshotView.center = currentPoint; // 計算截圖視圖和哪個可見cell相交 for (UICollectionViewCell *cell in self.collectionView.visibleCells) { // 當前隱藏的cell就不需要交換了,直接continue if ([self.collectionView indexPathForCell:cell] == self.oldIndexPath) { continue; } // 計算中心距 CGFloat space = sqrtf(pow(self.snapshotView.center.x - cell.center.x, 2) + powf(self.snapshotView.center.y - cell.center.y, 2)); // 如果相交一半就移動 if (space <= self.snapshotView.bounds.size.width / 2) { self.moveIndexPath = [self.collectionView indexPathForCell:cell]; //移動 會調用willMoveToIndexPath方法更新數據源 [self.collectionView moveItemAtIndexPath:self.oldIndexPath toIndexPath:self.moveIndexPath]; //設置移動后的起始indexPath self.oldIndexPath = self.moveIndexPath; break; } } } break; default: { // 手勢結束和其他狀態 UICollectionViewCell *cell = [self.collectionView cellForItemAtIndexPath:self.oldIndexPath]; // 結束動畫過程中停止交互,防止出問題 self.collectionView.userInteractionEnabled = NO; // 給截圖視圖一個動畫移動到隱藏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) { // 移除截圖視圖,顯示隱藏的cell并開始交互 [self.snapshotView removeFromSuperview]; cell.hidden = NO; self.collectionView.userInteractionEnabled = YES; }]; } break; }}三.iOS9之后添加的API如下
// Support for reordering- (BOOL)beginInteractiveMovementForItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0); // returns NO if reordering was prevented from beginning - otherwise YES- (void)updateInteractiveMovementTargetPosition:(CGPoint)targetPosition NS_AVAILABLE_IOS(9_0);- (void)endInteractiveMovement NS_AVAILABLE_IOS(9_0);- (void)cancelInteractiveMovement NS_AVAILABLE_IOS(9_0);
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