当按下UITextField / UISearchBar的清除按钮时，iPhone会执行操作

Question

Is it possible to gain access to a delegate method that will allow additional actions to be performed when the "clear" button is pressed on a UITextField / UISearchBar?

Thanks

Answer 1

See: UITextFieldDelegate Protocol Reference

If you set your view controller as the delegate for your text field (can be done in interface builder), you can use:

- (void)clearSearchTextField
{
  ...
}

- (BOOL)textFieldShouldClear:(UITextField *)textField
{
  if (textField == self.searchTextField) [self clearSearchTextField];
  return YES;
}

Answer 2

For Swift 3:

To perform an action when the "clear" button is pressed on a UITextField

func textFieldShouldClear(_ textField: UITextField) -> Bool {
    if textField == yourTextFieldName {
        // do some action
    }
    return true
}

Answer 3

For a UISearchBar you will want to implement func searchBar(searchBar: UISearchBar, textDidChange searchText: String) .

This is triggered before func searchBarTextDidBeginEditing(searchBar: UISearchBar) and before func searchBar(searchBar: UISearchBar, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool as well.

You implementation should look something like this:

func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {
        if searchText == "" {
            //Code to execute when search is cleared
        }
    }

Answer 4

When you clear the text field several events will happen that you will have access to through either the UISearchDisplayDelegate or the UISearchBarDelegate such as searchBar:textDidChange and searchDisplayController:shouldReloadTableForSearchString

This will also cause the search table to hide so it will trigger

searchDisplayController:willHideSearchResultsTableView  
searchDisplayController:didHideSearchResultsTableView

When the search table will hide you can check if the search text is empty and then do whatever you need to do.

Answer 5

请参阅我的回答： https ：//stackoverflow.com/a/3852509/91458 - 它适用于searchBar，但也应该应用于textField。