objective-c - 将 NSAlert beginSheetModalForWindow 与 contextInfo 结合使用

Question

当用户点击默认按钮时，我从下面的警报表代码中收到以下错误:

-[NSRectSet objectForKey:]: unrecognized selector sent to instance 0x400876300

顺便说一句，代码在 Snow Leopard 中运行良好，但在 Lion 中出现问题。

NSMutableDictionary * extrasDict = [[NSMutableDictionary alloc] init];
[extrasDict setObject:@"http://www.google.com" forKey:@"link"];

NSAlert * alert = [NSAlert alertWithMessageText:@"Published Successfully"
                                  defaultButton:@"View Collage on Facebook"
                                alternateButton:nil
                                    otherButton:@"Cancel"
                      informativeTextWithFormat:@"Successfully published to Facebook."];

[alert beginSheetModalForWindow:myWindow
                  modalDelegate:self
                 didEndSelector:@selector(publishedSuccessfullyDidEnd:returnCode:contextInfo:)
                    contextInfo:extrasDict];             


- (void)publishedSuccessfullyDidEnd:(NSAlert *)alert
                         returnCode:(NSInteger)returnCode
                        contextInfo:(void *)contextInfo {
    if (returnCode == NSAlertDefaultReturn) {
        [[NSWorkspace sharedWorkspace] openURL:
         [NSURL URLWithString:[(NSDictionary*)contextInfo objectForKey:@"link"]]]; 
    }       
}

Answer 1

如果您使用垃圾收集，请将 extrasDict 存储在实例变量中 - 任何地方，都没关系 - 因此它不会在运行循环结束时释放。您需要保留字典，直到 didEndSelector 可以对其进行操作。