UISearchBar不显示范围栏

Question

我使用下面的代码来显示带有范围栏的UISearchBar。

UISearchBar *searchBar = [[UISearchBar alloc]initWithFrame:CGRectMake(0, 0, 320, 45)]; 
searchBar.barStyle = UIBarStyleDefault; 
searchBar.showsCancelButton = NO; 
searchBar.autocorrectionType = UITextAutocorrectionTypeNo; 
searchBar.autocapitalizationType = UITextAutocapitalizationTypeNone; 

searchBar.scopeButtonTitles = [NSArray arrayWithObjects:@"One", @"Two", nil]; 
searchBar.showsScopeBar = YES; 

self.tableView.tableHeaderView = searchBar; 

[searchBar release]; 

但是，范围栏从不显示。为什么没有显示，我该如何解决这个问题？

Answer 1

在initWithFrame:CGRectMake(0, 0, 320, 45)中，高度只是搜索栏的高度，不包括范围栏。试着用一些替代，如：

UISearchBar *searchBar = [[UISearchBar alloc]initWithFrame:CGRectMake(0, 0, 320, 90)]; 

Answer 2

(void) searchDisplayControllerWillBeginSearch:(UISearchDisplayController *) 
controller{ 
    _searchBar.showsScopeBar = YES; 
    [_searchBar sizeToFit]; 
} 

Answer 3

如果没有UISearchDisplayController可用做，你可以尝试使用UISearchBarDelegate回调：

- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)searchBar 
{ 
    self.searchBar.showsScopeBar = YES; 
    [self.searchBar sizeToFit]; 
    return YES; 
} 

- (void)searchBarTextDidEndEditing:(UISearchBar *)searchBar{ 
    self.searchBar.showsScopeBar = NO; 
    [self.searchBar sizeToFit]; 
}