ios开发之UITextField、UITextView限制最大输入数

UITextField

NSInteger const maxNum = 20;

[self.textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

#pragma mark -------UITextFiledDelegate

-(void)textFieldDidChange:(UITextField *)textField
{
NSString *toBeString = textField.text;

//获取高亮部分
UITextRange *selectedRange = [textField markedTextRange];
UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
if (!position || !selectedRange)
{
if (toBeString.length > maxNum)
{
NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:maxNum];
if (rangeIndex.length == 1)
{
textField.text = [toBeString substringToIndex:maxNum];
}
else
{
NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, maxNum)];
textField.text = [toBeString substringWithRange:rangeRange];
}
}
}
}

UITextView

NSInteger const maxNum = 20;

#pragma mark ------- UITextViewDelegate

- (void)textViewDidChange:(UITextView *)textView
{
if (textView.text.length >= maxDetailNum) {
textView.text = [textView.text substringToIndex:maxDetailNum];
}
}