UITextFieldに入力文字数を表示する

これはなに？

• タイトルどおり
• 検索しても同じようなのを見かけなかったので投稿してみた
• サンプルでは11文字以上になると赤字になるようにした

やり方

1.UITextField作る

ViewController.m

    self.textField = [[UITextField alloc] initWithFrame:CGRectMake(14, 0, self.view.frame.size.width - 14, 44)];
    self.textField.placeholder = @"何か入力してください。";
    self.textField.clearButtonMode = UITextFieldViewModeWhileEditing;
    self.textField.textAlignment = NSTextAlignmentLeft;
    self.textField.backgroundColor = [UIColor clearColor];
    self.textField.delegate = self;
    [self.textField addTarget:self
                       action:@selector(textFieldEditing:)
             forControlEvents:UIControlEventEditingChanged];

2.文字数を表示するUILabel

ViewController.m

    self.currentLengthLabel = [[UILabel alloc] initWithFrame:CGRectMake(self.view.frame.size.width-50, 2, 30, 10)];
    self.currentLengthLabel.font = [UIFont systemFontOfSize:10];
    self.currentLengthLabel.hidden = YES;
    self.currentLengthLabel.textAlignment = NSTextAlignmentRight;
    [self changeCurrentLengthText:0];
    [self.textField addSubview:self.currentLengthLabel];

3.文字数の取得

ViewController.m

#pragma mark - 文字数カウント
- (void)changeCurrentLengthText:(NSInteger)currentLength
{
    self.currentLengthLabel.text = [NSString stringWithFormat:@"%ld/%ld", (long)currentLength, (long)MAXTITLE];

    if (currentLength > MAXTITLE) {
        self.currentLengthLabel.textColor = [UIColor redColor];
    } else {
        self.currentLengthLabel.textColor = [UIColor lightGrayColor];
    }
}

4.UITextFieldDelegateで文字数の表示の調整

ViewController.m

#pragma mark - <UITextFieldDelegate>
- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    self.currentLengthLabel.hidden = NO;
    [self changeCurrentLengthText:textField.text.length];
}

- (void)textFieldDidEndEditing:(UITextField *)textField
{
    self.currentLengthLabel.hidden = YES;
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [self.textField resignFirstResponder];
    return YES;
}

- (BOOL)textFieldShouldClear:(UITextField *)textField
{
    [self changeCurrentLengthText:0];
    return YES;
}

- (void)textFieldEditing:(UITextField*)textField
{
    [self changeCurrentLengthText:textField.text.length];
}