【移動(dòng)應(yīng)用開發(fā)技術(shù)】怎么在iOS中使用UICollectionView實(shí)現(xiàn)拖拽效果

【移動(dòng)應(yīng)用開發(fā)技術(shù)】怎么在iOS中使用UICollectionView實(shí)現(xiàn)拖拽效果

本篇文章為大家展示了怎么在iOS中使用UICollectionView實(shí)現(xiàn)拖拽效果，內(nèi)容簡(jiǎn)明扼要并且容易理解，絕對(duì)能使你眼前一亮，通過(guò)這篇文章的詳細(xì)介紹希望你能有所收獲。1.創(chuàng)建工程項(xiàng)目和視圖控制器,如下圖2.聲明對(duì)象和設(shè)置代理和數(shù)據(jù)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;

@end3.初始化UICollectionView,并添加長(zhǎng)按手勢(shì),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(zhǎng)按手勢(shì)

UILongPressGestureRecognizer

*longPress

=

[[UILongPressGestureRecognizer

alloc]

initWithTarget:self

action:@selector(handlelongGesture:)];

[collectionView

addGestureRecognizer:longPress];4.實(shí)例化數(shù)據(jù)源,(50個(gè)隨機(jī)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(shí)現(xiàn)UICollectionView的UICollectionViewDataSource的兩個(gè)必須實(shí)現(xiàn)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(diǎn)來(lái)了,實(shí)現(xiàn)長(zhǎng)按手勢(shì)方法#pragma

mark

-

長(zhǎng)按手勢(shì)

-

(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(shí)現(xiàn)#pragma

mark

-

iOS9

之后的方法

-

(BOOL)collectionView:(UICollectionView

*)collectionView

canMoveItemAtIndexPath:(NSIndexPath

*)indexPath

{

//

返回YES允許row移動(dòng)

return

YES;

}

-

(void)collectionView:(UICollectionView

*)collectionView

moveItemAtIndexPath:(NSIndexPath

*)sourceIndexPath

toIndexPath:(NSIndexPath

*)destinationIndexPath

{

//取出移動(dòng)row數(shù)據(jù)

id

color

=

self.dataArr[sourceIndexPath.row];

//從數(shù)據(jù)源中移除該數(shù)據(jù)

[self.dataArr

removeObject:color];

//將數(shù)據(jù)插入到數(shù)據(jù)源中的目標(biāo)位置

[self.dataArr

insertObject:color

atIndex:destinationIndexPath.row];

}

-

(void)iOS9_Action:(UILongPressGestureRecognizer

*)longPress

{

switch

(longPress.state)

{

case

UIGestureRecognizerStateBegan:

{

//手勢(shì)開始

//判斷手勢(shì)落點(diǎn)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(dòng)cell

[self.collectionView

beginInteractiveMovementForItemAtIndexPath:indexPath];

}

break;

case

UIGestureRecognizerStateChanged:

{

//

手勢(shì)改變

//

iOS9方法

移動(dòng)過(guò)程中隨時(shí)更新cell位置

[self.collectionView

updateInteractiveMovementTargetPosition:[longPress

locationInView:self.collectionView]];

}

break;

case

UIGestureRecognizerStateEnded:

{

//

手勢(shì)結(jié)束

//

iOS9方法

移動(dòng)結(jié)束后關(guān)閉cell移動(dòng)

[self.collectionView

endInteractiveMovement];

}

break;

default:

//手勢(shì)其他狀態(tài)

[self.collectionView

cancelInteractiveMovement];

break;

}

}8.iOS9之前的實(shí)現(xiàn)#pragma

mark

-

iOS9

之前的方法

-

(void)action:(UILongPressGestureRecognizer

*)longPress

{

switch

(longPress.state)

{

case

UIGestureRecognizerStateBegan:

{

//

手勢(shì)開始

//判斷手勢(shì)落點(diǎn)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(tǒng)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(dāng)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(shì)改變

//當(dāng)前手指位置

截圖視圖位置隨著手指移動(dòng)而移動(dòng)

CGPoint

currentPoint

=

[longPress

locationInView:self.collectionView];

self.snapshotView.center

=

currentPoint;

//

計(jì)算截圖視圖和哪個(gè)可見(jiàn)cell相交

for

(UICollectionViewCell

*cell

in

self.collectionView.visibleCells)

{

//

當(dāng)前隱藏的cell就不需要交換了,直接continue

if

([self.collectionView

indexPathForCell:cell]

==

self.oldIndexPath)

{

continue;

}

//

計(jì)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(dòng)

if

(space

<=

self.snapshotView.bounds.size.width

/

2)

{

self.moveIndexPath

=

[self.collectionView

indexPathForCell:cell];

//移動(dòng)

會(huì)調(diào)用willMoveToIndexPath方法更新數(shù)據(jù)源

[self.collectionView

moveItemAtIndexPath:self.oldIndexPath

toIndexPath:self.moveIndexPath];

//設(shè)置移動(dòng)后的起始indexPath

self.oldIndexPath

=

self.moveIndexPath;

break;

}

}

}

break;

default:

{

//

手勢(shì)結(jié)束和其他狀態(tài)

UICollectionViewCell

*cell

=

[self.collectionView

cellForItemAtIndexPath:self.oldIndexPath];

//

結(jié)束動(dòng)畫過(guò)程中停止交互,防止出問(wèn)題

self.collectionView.userInteractionEnabled

=

NO;

//

給截圖視圖一個(gè)動(dòng)畫移動(dòng)到隱藏cell的新位置

[UIView

animateWithDuration:0.25

animations:^{

self.