取內容

NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
    NSArray *types = [pasteboard types];
    if ([types containsObject:NSPasteboardTypeString]) {
        NSString *s = [pasteboard stringForType:NSPasteboardTypeString];
        //do something...
    }

放內容

NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
[pasteboard clearContents];  //必須清空，否則setString會失敗。
[pasteboard setString:@"Hello World!" forType:NSStringPboardType];