iOS UISearchBar 設置取消按鈕，回收鍵盤，並修改cancel為“取消”

繼承協議：

UISearchBarDelegate

在代理方法中設置：

#pragma mark --- 搜索框開始編輯 ---
- (void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar {
    [UIView animateWithDuration:0.3 animations:^{
        //        self.navigationController.navigationBarHidden = YES;
        //        _searchBar.frame = CGRectMake(0, 20, kScreenWidth, 44);
        _searchBar.showsCancelButton = YES;
        
        for (id obj in [searchBar subviews]) {
            if ([obj isKindOfClass:[UIView class]]) {
                for (id obj2 in [obj subviews]) {
                    if ([obj2 isKindOfClass:[UIButton class]]) {
                        UIButton *btn = (UIButton *)obj2;
                        [btn setTitle:@"取消" forState:UIControlStateNormal];
                        [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
                    }
                }
            }
        }
        
    }];
}