无法拖放到NSCollectionView上 [英] Cannot get drag and drop to work onto NSCollectionView

问题描述

我可能犯了一个简单的错误，但是我根本无法将文件拖放到NSCollectionView上，即使以最基本的方式工作也是如此.

There is probably a simple mistake that I'm making, but I simply cannot get dropping of files onto an NSCollectionView to work even in the most basic way.

在一个测试项目中，我在窗口上有一个NSCollectionView，而视图控制器既是其委托者，又是数据源.我希望能够将文件从Finder拖到该集合视图中.

In a test project, I have an NSCollectionView on a window, and the view controller is both its delegate and data source. I want to be able to drag files from the Finder onto this collection view.

通过阅读文档，我要做的就是:

From reading the docs, all I should have to do is:

注册拖动类型:

- (void)viewDidLoad {

    [super viewDidLoad];
    // Do any additional setup after loading the view.

    NSLog(@"Registering dragged types for collection view: %@", self.collectionView);
    [self.collectionView registerForDraggedTypes:@[NSFilenamesPboardType]];
    [self.collectionView setDraggingSourceOperationMask:NSDragOperationEvery forLocal:YES];
    [self.collectionView setDraggingSourceOperationMask:NSDragOperationEvery forLocal:NO];
}

然后实现这两种方法:

-(NSDragOperation)collectionView:(NSCollectionView *)collectionView validateDrop:(id<NSDraggingInfo>)draggingInfo proposedIndex:(NSInteger *)proposedDropIndex dropOperation:(NSCollectionViewDropOperation *)proposedDropOperation {

    NSLog(@"Validate drop: %@", draggingInfo);

    return NSDragOperationMove;
}

-(BOOL)collectionView:(NSCollectionView *)collectionView acceptDrop:(id<NSDraggingInfo>)draggingInfo index:(NSInteger)index dropOperation:(NSCollectionViewDropOperation)dropOperation {

    NSLog(@"Accept drop: %@", draggingInfo);

    return YES;
}

但是，当我尝试将一个项目拖到集合视图上时，这两个方法都没有被调用过，这使我认为 registerForDraggedTypes:调用未按预期工作.

But none of the two methods is ever called, when I try to drag an item onto the collection view, which makes me think that the registerForDraggedTypes: call is not working as expected.

这里可能是什么问题?我还需要研究什么?

What can be the issue here? What else do I have to look into?

推荐答案

从OS X 10.11起， NSCollectionViewDelegate 方法采用索引路径而不是索引路径.例如

From OS X 10.11 the NSCollectionViewDelegate methods take an index path instead of an index. For instance in

-(NSDragOperation)collectionView:(NSCollectionView *)collectionView validateDrop:(id<NSDraggingInfo>)draggingInfo proposedIndex:(NSInteger *)proposedDropIndex dropOperation:(NSCollectionViewDropOperation *)proposedDropOperation

proposedIndex:参数替换为 proposedIndexPath:

- (NSDragOperation)collectionView:(NSCollectionView *)collectionView validateDrop:(id <NSDraggingInfo>)draggingInfo proposedIndexPath:(NSIndexPath * __nonnull * __nonnull)proposedDropIndexPath dropOperation:(NSCollectionViewDropOperation *)proposedDropOperation

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