(iOS/Objective-C) 有条件地向 UIActionSheet 添加不同按钮的更好方法？

Question

在我的 iOS 应用程序中，我向用户呈现一个 UIActionSheet；然而，UIActionSheet 必须能够针对不同情况呈现不同的按钮（例如，如果用户没有运行 iOS 5，则 Twitter 支持不可用，因此不要显示“Tweet this”按钮；如果 AirPrint 不可用，则用户可以不打印，所以不要显示“打印”按钮等。）现在我以一种非常脑死亡的方式实现了这一点，基本上使用了一堆 if-then-else 语句（见下文）。有没有更干净的方法来做到这一点？

if(NSClassFromString(@"TWTweetComposeViewController"))  {
    if ([TWTweetComposeViewController canSendTweet]) {
        actionSheet = [[UIActionSheet alloc] initWithTitle:NSLocalizedString(@"Options", @"Options string")
                                                             delegate:self
                                         cancelButtonTitle:NSLocalizedString(@"Cancel", @"Cancel button")
                                               destructiveButtonTitle:nil
                                         otherButtonTitles:NSLocalizedString(@"Open in Safari", @"Open in Safari button"), NSLocalizedString(@"E-mail to a Friend", @"E-mail to a Friend button"), NSLocalizedString(@"Print", @"Print button"), NSLocalizedString(@"Tweet This", @"Tweet This button"), nil];
    } else {
        actionSheet = [[UIActionSheet alloc] initWithTitle:NSLocalizedString(@"Options", @"Options string")
                                                  delegate:self
                                         cancelButtonTitle:NSLocalizedString(@"Cancel", @"Cancel button")
                                    destructiveButtonTitle:nil
                                         otherButtonTitles:NSLocalizedString(@"Open in Safari", @"Open in Safari button"), NSLocalizedString(@"E-mail to a Friend", @"E-mail to a Friend button"), NSLocalizedString(@"Print", @"Print button"), nil];
    }
} else {
    actionSheet = [[UIActionSheet alloc] initWithTitle:NSLocalizedString(@"Options", @"Options string")
                                              delegate:self
                                     cancelButtonTitle:NSLocalizedString(@"Cancel", @"Cancel button")
                                destructiveButtonTitle:nil
                                     otherButtonTitles:NSLocalizedString(@"Open in Safari", @"Open in Safari button"), NSLocalizedString(@"E-mail to a Friend", @"E-mail to a Friend button"), NSLocalizedString(@"Print", @"Print button"), nil];
}

Answer 1

这与使用 addButtonWithTitle:(NSString *)title 一样简单：

actionSheet = [[UIActionSheet alloc] initWithTitle:NSLocalizedString(@"Options", @"Options string")
                                          delegate:self
                                 cancelButtonTitle:NSLocalizedString(@"Cancel", @"Cancel button")
                            destructiveButtonTitle:nil
                                 otherButtonTitles:NSLocalizedString(@"Open in Safari", @"Open in Safari button"), NSLocalizedString(@"E-mail to a Friend", @"E-mail to a Friend button"), NSLocalizedString(@"Print", @"Print button"), nil];

if(NSClassFromString(@"TWTweetComposeViewController"))
    if ([TWTweetComposeViewController canSendTweet])
        [actionSheet addButtonWithTitle:NSLocalizedString(@"Tweet This", @"Tweet This button")];