項目中首頁按鈕按照需求需要實現拖拽排序並且記錄排序後的佈局,下次再進入APP後展示排序後的佈局。
功能分析
實現此功能需要實現兩個點,第一就是拖拽排序的實現,第二就是存儲排序後的佈局,針對第一個功能點,拖拽排序:這個可以使用collectionView系統自帶的功能來實現,針對第二個功能點,我使用NSUserDefaults
本地存儲盛放collectionViewCell
內容的數組。
整體效果如圖:
本地存儲的實現
每個cell由背景圖片和title組成,NSDictionary *dic1 = @{@"title":@"標題", @"img":@"bgImg"};
每個字典存放兩個字段,根據需求,創建相應的字典,NSArray *tempArr = @[dic1,dic2,dic3,dic4,dic5]``[self.homeBtnsArr addObjectsFromArray:tempArr];
將字典放在數組中,便於在collectionView的代理方法中使用,[[NSUserDefaults standardUserDefaults] setObject:self.homeBtnsArr forKey:@"stuHomeBtns"];
將數組做本地儲存,在每次進入界面時,先去NSUserDefaults
中查找存放的數組,再去使用。
拖拽移動功能的實現
1、創建collectionView
UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
flowLayout.itemSize = CGSizeMake((SCREEN_WIDTH-50.0)/4, 85);
flowLayout.minimumLineSpacing = 0.1;
flowLayout.minimumInteritemSpacing = 0.1;
UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:flowLayout];
collectionView.backgroundColor = [UIColor whiteColor];
collectionView.delegate = self;
collectionView.dataSource = self;
self.collectionView = collectionView;
[self addSubview:collectionView];
[collectionView makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(0);
}];
[collectionView registerClass:[HomeSortBtnCell class] forCellWithReuseIdentifier:@"HomeSortBtnCell"];
2、在collectionView上添加長按手勢
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handlelongGesture:)];
[collectionView addGestureRecognizer:longPress];
3、長按手勢響應方法
#pragma mark 長按響應方法
- (void)handlelongGesture:(UILongPressGestureRecognizer *)longPress {
[self action:longPress];
}
4、處理長按手勢
- (void)action:longPress:(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;
}
HomeSortBtnCell *cell = (HomeSortBtnCell *)[self.collectionView cellForItemAtIndexPath:indexPath];
[self bringSubviewToFront:cell];
//iOS9 方法 移動cell
[self.collectionView beginInteractiveMovementForItemAtIndexPath:indexPath];
}
break;
case UIGestureRecognizerStateChanged:
{
//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 移動結束後關閉cell移動
[self.collectionView endInteractiveMovement];
}
break;
default:
[self.collectionView cancelInteractiveMovement];
break;
}
}
這裏處理長按手勢的時候,(一)、判斷手勢開始,判斷手勢落點位置是否在collectionView的cell上,collectionView系統的方法:
indexPathForItemAtPoint:
這裏的point爲:[longPress locationInView:self.collectionView]
,獲取到手勢落點的indexPath後,根據indexPath查找到相應位置的cell,然後[self bringSubviewToFront:cell];
將cell提到前層展示,給人以懸浮的感覺,這時就開始了collectionView的移動操作:[self.collectionView beginInteractiveMovementForItemAtIndexPath:indexPath];
。(二)、當手勢在移動的過程中,collectionView隨時更新cell的位置:[self.collectionView updateInteractiveMovementTargetPosition:[longPress locationInView:self.collectionView]];
。(三)、手勢結束後,collectionView也隨之關閉cell的移動:[self.collectionView endInteractiveMovement];
。
這裏不僅僅需要處理手勢事件,還需要遵循collectionView相關的代理方法:
//開啓collectionView可以移動
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath {
return YES;
}
//處理collectionView移動過程中的數據操作
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath {
//取出移動row 數據
NSDictionary *dic = self.viewModel.homeBtnsArr[sourceIndexPath.row];
//從數據源中移除該數據
[self.viewModel.homeBtnsArr removeObject:dic];
//將數據插入到數據源中目標位置
[self.viewModel.homeBtnsArr insertObject:dic atIndex:destinationIndexPath.row];
NSArray *tempBtns = [self.viewModel.homeBtnsArr copy];
if ([self.viewModel fetchIsTeacherRole]) {
//教師端
[[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"teaHomeBtns"];
} else {
[[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"stuHomeBtns"];
}
}
在
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath
代理方法中,(一)、 //取出移動row 數據
NSDictionary dic = self.viewModel.homeBtnsArr[sourceIndexPath.row];(二)、//從數據源中移除該數據 [self.viewModel.homeBtnsArr removeObject:dic];
(三)、//將數據插入到數據源中目標位置 [self.viewModel.homeBtnsArr insertObject:dic atIndex:destinationIndexPath.row];
(四)、NSArray *tempBtns = [self.viewModel.homeBtnsArr copy];[[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"teaHomeBtns"];
將改變後的cell內容數組存儲到本地。
以上就是iOS9及以上移動collectionViewCell的方法,我們利用系統封裝好的方法,相對比較容易的實現了功能。接下來看一下iOS9以下我們需要怎麼實現
iOS9以下
#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;
}
HomeSortBtnCell *cell = (HomeSortBtnCell *)[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 addSubview:self.snapShotView = snapshotView];
//截圖後隱藏當前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;
}];
//取出移動row 數據
// NSDictionary *dic = self.viewModel.homeBtnsArr[self.oldIndexPath.row];
// //從數據源中移除該數據
// [self.viewModel.homeBtnsArr removeObject:dic];
}
break;
case UIGestureRecognizerStateChanged:
{
//手勢改變 當前手指位置 截圖視圖位置隨着手指移動而移動
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 (HomeSortBtnCell *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 = sqrt(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];
/*更新數據源 須在移動之前*/
//取出移動row 數據
NSDictionary *dic = self.viewModel.homeBtnsArr[self.oldIndexPath.row];
//從數據源中移除該數據
[self.viewModel.homeBtnsArr removeObject:dic];
//將數據插入到數據源中目標位置
[self.viewModel.homeBtnsArr insertObject:dic atIndex:self.moveIndexPath.row];
//移動 會調用MoveToIndexPath方法更新數據源
[self.collectionView moveItemAtIndexPath:self.oldIndexPath toIndexPath:self.moveIndexPath];
//設置移動後的起始indexPath
self.oldIndexPath = self.moveIndexPath;
break;
}
}
}
break;
default:
{
//手勢結束和其他狀態
HomeSortBtnCell *cell = (HomeSortBtnCell *)[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並開始交互
[self.snapShotView removeFromSuperview];
cell.hidden = NO;
self.collectionView.userInteractionEnabled = YES;
//本地存儲已修改的按鈕數組
NSArray *tempBtns = [self.viewModel.homeBtnsArr copy];
if ([self.viewModel fetchIsTeacherRole]) {
//教師端
[[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"teaHomeBtns"];
} else {
[[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"stuHomeBtns"];
}
}];
}
break;
}
}
iOS9以下就相對 麻煩些了,首先在手勢開始時,我們也同樣需要找到手勢落點所在位置的cell,然後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 addSubview:self.snapShotView = snapshotView]; //截圖後隱藏當前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; }];
這裏我們做這麼多的操作,在iOS9及以上我們相應做的操作是:[self bringSubviewToFront:cell]; //iOS9 方法 移動cell [self.collectionView beginInteractiveMovementForItemAtIndexPath:indexPath];
。當手勢發生改變,也就是我們開始移動的時候,截圖的視圖位置也隨着手指移動而移動CGPoint currentPoint = [longPress locationInView:self.collectionView]; self.snapShotView.center = currentPoint;
我們需要自己計算截圖視圖和哪個可見cell相交:for (HomeSortBtnCell *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 = sqrt(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]; /*更新數據源 須在移動之前*/ //取出移動row 數據 NSDictionary *dic = self.viewModel.homeBtnsArr[self.oldIndexPath.row]; //從數據源中移除該數據 [self.viewModel.homeBtnsArr removeObject:dic]; //將數據插入到數據源中目標位置 [self.viewModel.homeBtnsArr insertObject:dic atIndex:self.moveIndexPath.row]; //移動 會調用MoveToIndexPath方法更新數據源 [self.collectionView moveItemAtIndexPath:self.oldIndexPath toIndexPath:self.moveIndexPath]; //設置移動後的起始indexPath self.oldIndexPath = self.moveIndexPath; break; } }
手勢結束之後,我們需要將截圖的視圖隱藏移除,並且刷新當前視圖佈局:
//手勢結束和其他狀態 HomeSortBtnCell *cell = (HomeSortBtnCell *)[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並開始交互 [self.snapShotView removeFromSuperview]; cell.hidden = NO; self.collectionView.userInteractionEnabled = YES; //本地存儲已修改的按鈕數組 NSArray *tempBtns = [self.viewModel.homeBtnsArr copy]; if ([self.viewModel fetchIsTeacherRole]) { //教師端 [[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"teaHomeBtns"]; } else { [[NSUserDefaults standardUserDefaults] setObject:tempBtns forKey:@"stuHomeBtns"]; } }];