使用 NSPasteboard 剪切和粘贴文件答案

【问题标题】：Cut & paste of files with NSPasteboard使用 NSPasteboard 剪切和粘贴文件
【发布时间】：2012-05-23 20:29:41
【问题描述】：

我们应该如何使用NSPasteboard 剪切和粘贴文件？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，在我将 URL 写入粘贴板之后，我必须删除该文件。当我尝试粘贴该文件时，它不再存在并且我无法复制它。我应该在粘贴板上写点别的吗？我也想过将文件复制到一个临时隐藏的位置，但这似乎有点低效。还有其他解决办法吗？

【问题讨论】：

你可以看看这个（在这里阅读 cmets stackoverflow.com/questions/9409852/… ）评论说 cut 可能无法通过 api 获得。复制完成后有什么方法可以得到确认吗？因为那时您可以安全地删除文件
我已经读过了，它没有提供任何解决方案。

标签： objective-c cocoa copy-paste appkit nspasteboard

【解决方案1】：

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

来自Pasteboard.h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

【讨论】：