在UICollectionView中复制标注

Question

我在每个单元格中都有一个带UIImageView的UICollectionView,现在我想添加Copy Callout,就像在Photos.app中一样:

我在UICollectionViewDelegate中看到了这个方法:

- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath {
    return YES;
}

经过几分钟的研究后,我找到了UIMenuController类,据我所知,我必须使用它来获取菜单,但无论如何,我认为必须有更简单的方法然后创建UIGestureRecognizer,创建,定位等我的UIMenu.

我是在正确的轨道上吗？你怎么能实现这个功能？

Answer 1

是的,你走在正确的轨道上.您还可以使用此技术实现除剪切,复制和粘贴之外的自定义操作.

UICollectionView的自定义操作

// ViewController.h
@interface ViewController : UICollectionViewController

// ViewController.m
-(void)viewDidLoad
{
    [super viewDidLoad];
    self.collectionView.delegate = self;

    UIMenuItem *menuItem = [[UIMenuItem alloc] initWithTitle:@"Custom Action"
                                                      action:@selector(customAction:)];
    [[UIMenuController sharedMenuController] setMenuItems:[NSArray arrayWithObject:menuItem]];

}

#pragma mark - UICollectionViewDelegate methods
- (BOOL)collectionView:(UICollectionView *)collectionView
      canPerformAction:(SEL)action
    forItemAtIndexPath:(NSIndexPath *)indexPath
            withSender:(id)sender {
    return YES;  // YES for the Cut, copy, paste actions
}

- (BOOL)collectionView:(UICollectionView *)collectionView
shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath {
    return YES;
}

- (void)collectionView:(UICollectionView *)collectionView
         performAction:(SEL)action
    forItemAtIndexPath:(NSIndexPath *)indexPath
            withSender:(id)sender {
    NSLog(@"performAction");
}

#pragma mark - UIMenuController required methods
- (BOOL)canBecomeFirstResponder {
    // NOTE: The menu item will on iOS 6.0 without YES (May be optional on iOS 7.0)
    return YES;
}

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    NSLog(@"canPerformAction");
     // The selector(s) should match your UIMenuItem selector
    if (action == @selector(customAction:)) {
        return YES;
    }
    return NO;
}

#pragma mark - Custom Action(s)
- (void)customAction:(id)sender {
    NSLog(@"custom action! %@", sender);
}

注意:iOS 7.0会更改行为

1. 在您的UICollectionViewCell子类中,您需要添加自定义操作方法,否则不会显示任何内容.

   // Cell.m
   #import "Cell.h"
   
   @implementation Cell
   
   - (id)initWithFrame:(CGRect)frame {
       self = [super initWithFrame:frame];
       if (self) {
           // custom logic
       }
       return self;
   }
   
   - (void)customAction:(id)sender {
       NSLog(@"Hello");
   
       if([self.delegate respondsToSelector:@selector(customAction:forCell:)]) {
           [self.delegate customAction:sender forCell:self];
       }
   }
   @end
   

2. 您需要创建一个委托协议并在每个单元格上设置它以回调到维护UICollectionView的UIController.这是因为单元格对模型没有任何意义,因为它只涉及显示内容.

   // Cell.h
   #import <UIKit/UIKit.h>
   
   @class Cell; // Forward declare Custom Cell for the property
   
   @protocol MyMenuDelegate <NSObject>
   @optional
   - (void)customAction:(id)sender forCell:(Cell *)cell;
   @end
   
   @interface Cell : UICollectionViewCell
   
   @property (strong, nonatomic) UILabel* label;
   @property (weak, nonatomic) id<MyMenuDelegate> delegate;
   @end
   

3. 在您的ViewController或UICollectionViewController的子类中,您需要符合协议并实现新方法.

   // ViewController.m
   @interface ViewController () <MyMenuDelegate>
   @end
   
   // @implementation ViewController  ...
   
   - (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath;
   {
       Cell *cell = [cv dequeueReusableCellWithReuseIdentifier:@"MY_CELL" forIndexPath:indexPath];
       cell.delegate = self;
       return cell;
   }
   // ...
   
   // Delegate method for iOS 7.0 to get action from UICollectionViewCell
   - (void)customAction:(id)sender forCell:(Cell *)cell {
       NSLog(@"custom action! %@", sender);
   }
   

   

4. 可选:在UIView子类中,如果在此处实现canPerformAction方法,则可以覆盖默认的Cut,Copy,Paste,而不是在UIViewController中.否则,该行为将在您的自定义方法之前显示默认方法.

   // Cell.m
   - (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
       NSLog(@"canPerformAction");
       // The selector(s) should match your UIMenuItem selector
   
       NSLog(@"Sender: %@", sender);
       if (action == @selector(customAction:)) {
           return YES;
       }
       return NO;
   }
   

   

Answer 2

这是完整的解决方案:

- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath {
        return YES;
    }

- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender {
        if ([NSStringFromSelector(action) isEqualToString:@"copy:"])
            return YES;
        else
            return NO;
    }

- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender {
        if ([NSStringFromSelector(action) isEqualToString:@"copy:"]) {
            UIPasteboard *pasteBoard = [UIPasteboard pasteboardWithName:UIPasteboardNameGeneral create:NO];
            pasteBoard.persistent = YES;
            NSData *capturedImageData = UIImagePNGRepresentation([_capturedPhotos objectAtIndex:indexPath.row]);
            [pasteBoard setData:capturedImageData forPasteboardType:(NSString *)kUTTypePNG];
        }
    }

在我的情况下,我只允许在我的CollectionView中使用复制功能,如果按下复制,我将复制单元格内的图像到PasteBoard.

Answer 3

也许有点晚了但我可能会找到一个更好的解决方案,仍然搜索这个:

在你的UICollectionViewController的viewDidLoad中添加你的项目:

UIMenuItem *menuItem = [[UIMenuItem alloc] initWithTitle:@"Title" action:@selector(action:)];
[[UIMenuController sharedMenuController] setMenuItems:[NSArray arrayWithObject:menuItem]];

添加以下委托方法:

//This method is called instead of canPerformAction for each action (copy, cut and paste too)
- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender {
        if (action == @selector(action:)) {
            return YES;
        }
        return NO;
    }
    //Yes for showing menu in general
    - (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath {
        return YES;
    }

如果你还没有UICollectionViewCell的子类.添加为项目指定的方法:

- (void)action:(UIMenuController*)menuController {

}

这样您就不需要任何becomeFirstResponder或其他方法.如果您将单元格本身作为参数调用一般方法,则可以在一个位置执行所有操作,并且可以轻松处理不同的单元格.

编辑:不知何故,uicollectionview需要存在此方法(此方法不会调用您的自定义操作,我认为uicollectionview只检查存在)

- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender {

}