OC中限制字数的方法

我是用通知实现的，首先添加UITextFiled和UITextView的接收中心

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewNotifitionAction:) name:UITextViewTextDidChangeNotification object:nil];

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFieldNotifitionAction:) name:UITextFieldTextDidChangeNotification object:nil];

通知调用的方法

- (void)textViewNotifitionAction:(NSNotification *)userInfo{

    if (_textV.text.length>=10) {
        NSString *str = [_textV.text substringToIndex:10];
        _textV.text = str;
    }

}

- (void)textFieldNotifitionAction:(NSNotification *)userInfo{
    if (_textF.text.length>=10) {
        NSString *str = [_textF.text substringToIndex:10];
        _textF.text = str;
    }
}

Swift中限制字数的方法

设置接收中心

NSNotificationCenter.defaultCenter().addObserver(self, selector: "textViewNotifitionAction:", name: UITextViewTextDidChangeNotification, object: nil);
NSNotificationCenter.defaultCenter().addObserver(self, selector: "textFiledNotifitionAction:", name: UITextFieldTextDidChangeNotification, object: nil);

通知调用的方法

func textViewNotifitionAction(userInfo:NSNotification){
        let textVStr = textV.text as NSString;
        if (textVStr.length >= 10) {
            let str = textVStr.substringToIndex(10);
            textV.text = str;
        }

    }
func textFiledNotifitionAction(userInfo:NSNotification){
        let textFStr = textF.text! as NSString;
        if (textFStr.length >= 10) {
            let str = textFStr.substringToIndex(10);
            textF.text = str;
        }

    }