UISearchBar取消按钮Xcode4.3？

Question

如何使cancel按钮仅在用户开始向UISearchBar中输入文本时出现？

我试过了

- (void)searchBarTextDidBeginEditing:(UISearchBar *)aSearchBar {
self.searchBar.showsCancelButton = YES;
}

但是它不起作用，我不认为将它设置为"showsCancelButton“有什么错，因为即使我说

NSLog(@"Typing");

它不会打印到屏幕上。在Xcode4.3中有没有其他方法可以做到这一点？是否还有一种方法可以知道cancel按钮是否已被按下？

Answer 1

是否确定该类是searchBar的委托？尝试在viewDidLoad方法中设置self.searchBar.delegate=self;。

Answer 2

你的方法没有返回BOOLean值，'YES.‘’这应该是可行的：

// show search bar's cancel button when editing
- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)searchBar {

    searchBar.showsCancelButton = YES;

    return YES;
}
// hide search bar's cancel button when not editing
- (BOOL)searchBarShouldEndEditing:(UISearchBar *)searchBar {

    searchBar.showsCancelButton = NO;

    return YES;
}

Answer 3

试试这个：

- (void)searchBarTextDidBeginEditing:(UISearchBar *)aSearchBar {
  aSearchBar.showsCancelButton = YES;
}