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 Ios教程網 >> IOS編程開發 >> IOS開發綜合 >> 使用iOS控件UICollectionView生成可拖動的桌面的實例

使用iOS控件UICollectionView生成可拖動的桌面的實例

編輯：IOS開發綜合

一個App受歡迎的程度，一方面來源於它本身為用戶提供便捷的功能，另一方面則來源於它的UI。UI是用戶體驗重要的組成部分，構成UI的的元素恰恰離不開那些看似獨立的控件。在開發的過程中，大家對UITableView應該很熟悉吧！確實UITableView在處理數據顯示方面有著很強大的功能，例如網紅們使用的微博，微信社交軟件的聊天界面等等，這種流式布局使用UITableView簡直最合適不過了；但畢竟UITableView不是萬能的，當需要顯示橫縱向的數據時它就顯得捉襟見肘了，雖然這也難不倒我們程序猿但是何必要大費周章的去定義復雜的cell呢！UICollectionView就是專門用來應付這種布局的,使用UICollectionView可以給我們帶來以下幾點優勢：1.可以高度的定制內容展示的樣式 2.高效的管理大量的數據。

首先給大家看一下這個Demo的效果圖：

iOS設備不知道現在有沒有可以屏幕錄制的app,這樣我就可以把操作的動作用gif圖片po上來了，大家如果有推薦可以告訴我哈！關於拖動，長按圖片後就可以將圖片拖到你想要的位置上，另外的圖片則會依次排序，很順暢的體驗。

在使用UICollectionView的時後，我們的類需要實現這些協議:UICollectionViewDataSource,UICollectionViewDelegateFlowLayout,

UICollectionViewDelegate,UIGestureRecognizerDelegate。

UICollectionViewDataSource：和我們在UITableView中所需要實現的UITableViewDataSource是一個道理，它裡面包括以下這些API：

@protocol UICollectionViewDataSource <NSObject> 
@required 
 
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section; 
 
// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath: 
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath; 
 
@optional 
 
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView; 
 
// The view that is returned must be retrieved from a call to -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath: 
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath; 
 
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0); 
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath NS_AVAILABLE_IOS(9_0); 
 
@end

UICollectionViewDelegateFlowLayout：UICollectionViewFlowLayout是一個專門用來管理collectionView布局的類,可以通過實現以下函數來調整我們界面的樣式：

@protocol UICollectionViewDelegateFlowLayout <UICollectionViewDelegate> 
@optional 
 
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath; 
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section; 
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section; 
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section; 
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section; 
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section; 
 
@end

UICollectionViewDelegate：和UITableViewDelegate一樣，這裡就把它協議裡面的的函數po出來了,通過重寫裡面的函數，我們可以實現cell的點擊與拖動。

UIGestureRecognizerDelegate：由於我們還有一個拖動的功能，所以需要實現用戶手勢的協議。

好了，基礎的概念講了，現在我們就開始動手實現他吧！老樣子直接看源碼：

- (void)viewDidLoad { 
  [super viewDidLoad]; 
  // Do any additional setup after loading the view, typically from a nib. 
   
  //設置背景色 
  [self.view setBackgroundColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"back.jpg"]]]; 
  //設置數據源 
  self.dataSource = [[NSMutableArray alloc] initWithObjects: 
            @"1.png",@"2.png",@"3.png", @"4.png", @"5.png", @"6.png", @"7.png", @"8.png", @"9.png", @"10.png", @"11.jpg", @"12.JPG", 
            @"13.JPG", @"14.jpg", @"15.JPG", @"16.png", @"17.png", @"18.png", @"19.png", @"20.png", nil nil]; 
  //初始化布局 
  self.flow = [[UICollectionViewFlowLayout alloc] init]; 
  self.collect = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:self.flow]; 
  [self.collect setBackgroundColor:[UIColor clearColor]]; 
   
  //注冊cell 這一步必須要實現 
  [self.collect registerClass:[CustomCollectionCell class] forCellWithReuseIdentifier:@"CustomCell"]; 
   
  self.collect.delegate = self; 
  self.collect.dataSource = self; 
   
  [self.collect setFrame:self.view.bounds]; 
   
  //添加長按手勢 
  self.longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] init]; 
  [self.longPressGestureRecognizer addTarget:self action:@selector(handleLongPressRecognizer:)]; 
  [self.collect addGestureRecognizer:self.longPressGestureRecognizer]; 
   
  [self.view addSubview:self.collect]; 
}

在viewDidLoad函數中，初始化了一個UICollectionViewFlowLayout布局，並且需要配合UICollectionView來使用，兩者加一起來使用才能“完美”，想比UITableView 中Cell使用的不同，在UICollectionView中必須先對Cell進行注冊(RegisterClass)，不然會在運行過程中報錯。如何使排列的圖片可以拖動呢，在這裡我為UICollectionView添加了一個長按手勢UILongPressGestureRecognizer。當我們長按時會觸發handleLongPressRecognizer，代碼如下：

- (void)handleLongPressRecognizer:(UILongPressGestureRecognizer *)gesture{ 
  switch (gesture.state) { 
    case UIGestureRecognizerStateBegan:{ 
      NSIndexPath *path = [self.collect indexPathForItemAtPoint:[gesture locationInView:gesture.view]]; 
      if(path == nil){ 
        break; 
      } 
       
      [self.collect beginInteractiveMovementForItemAtIndexPath:path]; 
    } 
      break; 
    case UIGestureRecognizerStateChanged: 
      [self.collect updateInteractiveMovementTargetPosition:[gesture locationInView:gesture.view]]; 
      break; 
    case UIGestureRecognizerStateEnded: 
      [self.collect endInteractiveMovement]; 
      break; 
    default: 
      [self.collect cancelInteractiveMovement]; 
      break; 
  } 
}

好看的界面才能抓住用戶的心，這裡我自定義了Cell繼承自UICollectionViewCell，cell中展示的圖片會根據自身圖片的大小進行按比例縮放，這樣我們的桌面看上去就會有橫版圖片與豎版圖片，如果不自定義的話就都是方方正正的九宮格，還是花點心思自定義一下顯示效果吧！CustomCollectionCell的的代碼如下：

#import "CustomCollectionCell.h" 
 
@implementation CustomCollectionCell 
@synthesize imageV = _imageV; 
@synthesize labelV = _labelV; 
@synthesize boundView = _boundView; 
 
- (id)initWithFrame:(CGRect) frame{ 
  self = [super initWithFrame:frame]; 
  //init attributes 
  if(self){ 
    [self setBackgroundColor:[UIColor clearColor]]; 
    self.imageV = [[UIImageView alloc] initWithFrame:CGRectZero]; 
    self.labelV = [[UILabel alloc] initWithFrame:CGRectZero]; 
    self.boundView = [[UIView alloc] initWithFrame:CGRectZero]; 
    [self.boundView setBackgroundColor:[UIColor whiteColor]]; 
    [self.boundView addSubview:self.imageV]; 
    [self addSubview:self.boundView]; 
    [self addSubview:self.labelV]; 
  } 
   
  return self; 
} 
 
- (void)setImageWithText:(UIImage *)image text:(NSString *)text{ 
  if(!image){ 
    return; 
  } 
   
  CGFloat imgWidth = image.size.width; 
  CGFloat imgHeight = image.size.height; 
  CGFloat iconWidth = 0.0; 
  CGFloat iconHeight = 0.0; 
   
  if(imgWidth > imgHeight){ 
    iconHeight = roundf(((self.frame.size.width - 16)*imgHeight)/imgWidth); 
    iconWidth = self.frame.size.width - 16; 
    [self.boundView setFrame:CGRectMake(0, self.frame.size.height - iconHeight - 16, iconWidth + 16, iconHeight + 16)]; 
    [self.imageV setFrame:CGRectMake(8, 8, iconWidth, iconHeight)]; 
  }else{ 
    iconWidth = roundf(((self.frame.size.width - 16) *imgWidth)/imgHeight); 
    iconHeight = self.frame.size.height - 16; 
    [self.boundView setFrame:CGRectMake(roundf((self.frame.size.width - iconWidth)/2), 0, iconWidth + 16, iconHeight + 16)]; 
    [self.imageV setFrame:CGRectMake(8, 8, iconWidth, iconHeight)]; 
  } 
   
  [self.imageV setImage:image]; 
} 
 
@end

以上這些就是構成該Demo的重要組成部分了，UICollectionView還有很多的要素在這裡面沒有講到，往後我還會再研究這個控件更加高級的的使用，本篇就好比是餐前的開胃小菜吧，希望大家喜歡。附上這個例子的源碼：

@implementation ViewController 
@synthesize dataSource = _dataSource; 
@synthesize longPressGestureRecognizer = _longPressGestureRecognizer; 
@synthesize flow = _flow; 
@synthesize collect = _collect; 
 
- (void)viewDidLoad { 
  [super viewDidLoad]; 
  // Do any additional setup after loading the view, typically from a nib. 
   
  //設置背景色 
  [self.view setBackgroundColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"back.jpg"]]]; 
  //設置數據源 
  self.dataSource = [[NSMutableArray alloc] initWithObjects: 
            @"1.png",@"2.png",@"3.png", @"4.png", @"5.png", @"6.png", @"7.png", @"8.png", @"9.png", @"10.png", @"11.jpg", @"12.JPG", 
            @"13.JPG", @"14.jpg", @"15.JPG", @"16.png", @"17.png", @"18.png", @"19.png", @"20.png", nil nil]; 
  //初始化布局 
  self.flow = [[UICollectionViewFlowLayout alloc] init]; 
  self.collect = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:self.flow]; 
  [self.collect setBackgroundColor:[UIColor clearColor]]; 
   
  //注冊cell 這一步必須要實現 
  [self.collect registerClass:[CustomCollectionCell class] forCellWithReuseIdentifier:@"CustomCell"]; 
   
  self.collect.delegate = self; 
  self.collect.dataSource = self; 
   
  [self.collect setFrame:self.view.bounds]; 
   
  //添加長按手勢 
  self.longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] init]; 
  [self.longPressGestureRecognizer addTarget:self action:@selector(handleLongPressRecognizer:)]; 
  [self.collect addGestureRecognizer:self.longPressGestureRecognizer]; 
   
  [self.view addSubview:self.collect]; 
} 
 
- (void)didReceiveMemoryWarning { 
  [super didReceiveMemoryWarning]; 
  // Dispose of any resources that can be recreated. 
} 
 
- (void)handleLongPressRecognizer:(UILongPressGestureRecognizer *)gesture{ 
  switch (gesture.state) { 
    case UIGestureRecognizerStateBegan:{ 
      NSIndexPath *path = [self.collect indexPathForItemAtPoint:[gesture locationInView:gesture.view]]; 
      if(path == nil){ 
        break; 
      } 
       
      [self.collect beginInteractiveMovementForItemAtIndexPath:path]; 
    } 
      break; 
    case UIGestureRecognizerStateChanged: 
      [self.collect updateInteractiveMovementTargetPosition:[gesture locationInView:gesture.view]]; 
      break; 
    case UIGestureRecognizerStateEnded: 
      [self.collect endInteractiveMovement]; 
      break; 
    default: 
      [self.collect cancelInteractiveMovement]; 
      break; 
  } 
} 
 
#pragma mark UICollectionViewDataSource 
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ 
  return self.dataSource.count; 
} 
 
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{ 
  return 1; 
} 
 
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ 
  CustomCollectionCell * cell = (CustomCollectionCell *)[collectionView dequeueReusableCellWithReuseIdentifier:@"CustomCell" forIndexPath:indexPath]; 
  UIImage *image = [UIImage imageNamed:[self.dataSource objectAtIndex:indexPath.row]]; 
  [cell setImageWithText:image text:@""]; 
   
  return cell; 
} 
 
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath{ 
  return YES; 
} 
 
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath{ 
   
  id item = [self.dataSource objectAtIndex:sourceIndexPath.item]; 
  [self.dataSource removeObject:item]; 
   
  [self.dataSource insertObject:item atIndex:destinationIndexPath.item]; 
} 
 
#pragma mark UICollectionViewDelegate 
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{ 
  TestViewController *test = [[TestViewController alloc] initWithNibName:@"TestViewController" bundle:nil]; 
  NSString *imageName = [self.dataSource objectAtIndex:indexPath.row]; 
  test.imageName = imageName; 
   
  [self.navigationController pushViewController:test animated:YES]; 
} 
 
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath{ 
  return YES; 
} 
 
//選中放大效果 
- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath{ 
//  CustomCollectionCell * cell = (CustomCollectionCell *)[collectionView cellForItemAtIndexPath:indexPath]; 
//   
//  [UIView animateWithDuration:1 animations:^{ 
//    cell.transform = CGAffineTransformMakeScale(2.0f, 2.0f); 
//  }]; 
} 
 
//縮小效果 
- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath{ 
//  CustomCollectionCell * cell = (CustomCollectionCell *)[collectionView cellForItemAtIndexPath:indexPath]; 
//   
//  [UIView animateWithDuration:1 animations:^{ 
//    cell.transform = CGAffineTransformMakeScale(1.0f, 1.0f); 
//  }]; 
} 
 
 
#pragma mark UICollectionViewDelegateFlowLayout 
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{ 
   
  return CGSizeMake(100, 100); 
} 
 
/* 
 * 上左下右間距 
 */ 
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{ 
   
  return UIEdgeInsetsMake(15, 15, 15, 15); 
} 
 
/* 
 * item space 
 */ 
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{ 
   
  return 8; 
} 
 
/* 
 * 行距 20 
 */ 
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{ 
   
  return 10; 
}

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持本站。

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