iphone - 如何将焦点设置到 iPhone 中的下一个 uitextfield？

Question

我有 8 个用于密码的 uitextfields。每个文本字段包含密码中的一个字母。当我输入一个字母，然后按第二个键时，焦点将移动到下一个文本字段。但我希望，一旦我输入完第一个字符，焦点就应该移动到下一个文本字段，而无需按其他键或按 Tab 键。我怎样才能做到这一点？有相关示例代码教程吗？我使用的代码如下。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    [[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(keyPressed:) name: UITextFieldTextDidChangeNotification object: nil];
    // Try to find next responder

    UIResponder* nextResponder = [textField.superview viewWithTag:nextTag];
    if (nextResponder) {
        // Found next responder, so set it.
        //nextTag += 1;
        [nextResponder becomeFirstResponder];
        if ([nextResponder tag] == 308) {
            //[self performSelector:@selector(checkPassCode) withObject:nil afterDelay:0.0];
            [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(checkPassCode) userInfo:nil repeats:NO];
            lastResponder = nextResponder;
        }
        return YES;
    } else {
        [textField resignFirstResponder];
        return NO;
    }
}


-(void) keyPressed: (NSNotification*) notification
{
    nextTag += 1;
    [[NSNotificationCenter defaultCenter] removeObserver: self name:UITextFieldTextDidChangeNotification object: nil];
}

Answer 1

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    NSString *finalString = [textField.text stringByReplacingCharactersInRange:range withString:string];

    if ( [finalString length] > 0 ) {
        textField.text = string;

        UIResponder* nextResponder = [textField.superview viewWithTag:(textField.tag + 1)];
        if (nextResponder) {
            [nextResponder becomeFirstResponder];

            // Your code for checking it.
        }

        return NO;
    }

    return YES;
}

希望这有帮助。

swift 3.2

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let finalString: String? = (textField.text? as NSString).replacingCharacters(in: range, with: string)
    if (finalString?.characters.count ?? 0) > 0 {
        textField.text = string
        let nextResponder: UIResponder? = textField.superview?.viewWithTag((textField.tag + 1))
        if nextResponder != nil {
            nextResponder?.becomeFirstResponder()
            // Your code for checking it.
        }
        return false
    }
    return true
}

swift 4.1

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let finalString: String? = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
    if finalString?.count > 0 {
        textField.text = string
        let nextResponder: UIResponder? = textField.superview?.viewWithTag(textField.tag + 1)
        if nextResponder != nil {
            nextResponder?.becomeFirstResponder()
            // Your code for checking it.
        }
        return false
    }
    return true
}