将图像复制到粘贴板将jpeg转码为png

// copy to clipboard
UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
NSData *data = [NSData dataWithContentsOfFile:filePath];
[pasteboard setData:data forPasteboardType:@"public.jpeg"];

// copy from clipboard
UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
NSData *data = [pasteboard dataForPasteboardType:@"public.jpeg"];
NSString  *copyPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/image.jpg"];
[data writeToFile:copyPath atomically:YES];

NSPasteboard *pboard  = [NSPasteboard generalPasteboard];
[pboard declareTypes: [NSMutableArray arrayWithObject:
                       NSTIFFPboardType] owner: nil];
[pboard setData:[imgView.image TIFFRepresentation] forType:NSTIFFPboardType];

NSData *data = [[NSPasteboard generalPasteboard] dataForType:NSPasteboardTypeTIFF];
    if (data) {
           // Do your stuff here 
    }