剪切和使用NSPasteboard粘贴文件 [英] Cut & paste of files with NSPasteboard

问题描述

我们应该如何削减&使用NSPasteboard粘贴文件?目前，我通过写入和读取文件URL来实现复制和粘贴. cut的问题是，在将URL写入粘贴板之后，必须删除文件.当我尝试粘贴文件时，该文件已不存在，无法复制.我应该在粘贴板上写些其他内容吗?我还考虑过将文件复制到一个临时的隐藏位置，但这似乎效率不高.还有其他解决方案吗?

How are we supposed to cut & paste files using NSPasteboard? Currently I implemented copy and paste by writing and reading file URLs. The problem with cut is, that after I wrote the URL to the pasteboard, I have to remove the file. And when I try to paste the file it doesn't exist anymore and I can't copy it. Should I write something else onto the pasteboard? I also thought about copying the file to a temporary hidden location, but that seems to be a bit inefficient. Is there any other solution?

推荐答案

您可以使用kPasteboardTypeFilePromiseContent.在这种情况下，拖动源负责将文件写入目标位置，因此您可以移动文件而不是复制文件.

You can use kPasteboardTypeFilePromiseContent. In this case, the dragging source is responsible to write the file to the destination, so you can move the file instead of duplicating it.

Pasteboard.h中的文档:

/*
 *  Pasteboard File Promising
 *  
 *  Summary:
 *    With the FSSpec type being deprecated and removed for 64 bit it is necessary
 *    to introduce a replacement for kDragFlavorTypePromiseHFS. The replacement comes
 *    in the form of two new Uniform Type Identifiers specifically for use with the
 *    pasteboard and promised files. Like the old HFS promise mechanism, the new UTI
 *    based method still requires a multistage handshake between sender and receiver
 *    but the process is somewhat simplified.
 *    
 *    Order of operations on copy or drag
 *    
 *    1) The sender promises kPasteboardTypeFileURLPromise for a file yet to be created.
 *    2) The sender adds kPasteboardTypeFilePromiseContent containing the UTI describing
 *          the file's content.
 *    
 *    Order of operations on paste or drop
 *    
 *    3) The receiver asks for kPasteboardTypeFilePromiseContent to decide if it wants the file.
 *    4) The receiver sets the paste location with PasteboardSetPasteLocation.
 *    5) The receiver asks for kPasteboardTypeFileURLPromise.
 *    6) The sender's promise callback for kPasteboardTypeFileURLPromise is called.
 *    7) The sender uses PasteboardCopyPasteLocation to retrieve the paste location, creates the file
 *          and keeps its kPasteboardTypeFileURLPromise promise.
 *
 *    Automatic translation support has been added so clients operating in the modern
 *    kPasteboardTypeFileURLPromise and kPasteboardTypeFilePromiseContent world can continue
 *    to communicate properly with clients using the traditional kDragFlavorTypePromiseHFS and
 *    kDragPromisedFlavor model.
 */

示例:

@implementation NSPasteboard (DestinationFolder)

- (NSURL*)pasteLocation
{
    NSURL* fileURL = nil;
    PasteboardRef pboardRef = NULL;
    PasteboardCreate((CFStringRef)[self name], &pboardRef);
    if (pboardRef != NULL) {
        PasteboardSynchronize(pboardRef);
        PasteboardCopyPasteLocation(pboardRef, (CFURLRef*)&fileURL);
        CFRelease(pboardRef);
    }
    return [fileURL autorelease];
}

- (void)setPasteLocation:(NSURL *)url
{
    PasteboardRef pboardRef = NULL;
    PasteboardCreate((CFStringRef)[self name], &pboardRef);
    if (pboardRef != NULL) {
        PasteboardSynchronize(pboardRef);
        PasteboardSetPasteLocation(pboardRef, (CFURLRef)url);
        CFRelease(pboardRef);
    }
}

@end

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