項(xiàng)目中會(huì)遇到各種限制字?jǐn)?shù)的需求，簡(jiǎn)單做個(gè)筆記。

//遵循協(xié)議<UITextFieldDelegate,UITextViewDelegate>
//實(shí)時(shí)監(jiān)控
 [_nameTextField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

#pragma mark - TextField Delegate
- (BOOL)textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString*)string
{
    //限制只可以輸入數(shù)字
    if (textField == _phoneTextField || textField == _registerText) {
        NSCharacterSet * cs = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789"] invertedSet];
        NSString * filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
        BOOL basicTest = [string isEqualToString:filtered];
        if(!basicTest) {
            [self showTextView:self.view message:@"請(qǐng)輸入數(shù)字"];
            return NO;
        }
    }
    return YES;
}

//點(diǎn)擊return按鍵收回鍵盤
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [self.view endEditing:YES];
    return YES;
}

//簡(jiǎn)單實(shí)現(xiàn)了 點(diǎn)擊 某個(gè)textField 整體頁(yè)面上移 保證不會(huì)被鍵盤遮蓋
- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    if (textField == _positionTextField ) {
        [UIView animateWithDuration:0.2 animations:^{
            _scrollView.contentOffset = CGPointMake(0, 40);
        }];
    }else if (textField == _telTextField)
    {
        [UIView animateWithDuration:0.2 animations:^{
            _scrollView.contentOffset = CGPointMake(0, 50);
        }];
    }else if (textField == _emailTextField)
    {
        [UIView animateWithDuration:0.2 animations:^{
            _scrollView.contentOffset = CGPointMake(0, 60);
        }];
    }
}

//限制輸入字?jǐn)?shù)
- (void)textFieldDidChange:(UITextField *)textField
{
    NSInteger kMaxLength = 10 ;    
    NSString *toBeString = textField.text;
    NSString *lang = [[UIApplication sharedApplication]textInputMode].primaryLanguage; //ios7之前使用[UITextInputMode currentInputMode].primaryLanguage
    if ([lang isEqualToString:@"zh-Hans"]) { //中文輸入
        UITextRange *selectedRange = [textField markedTextRange];
        //獲取高亮部分
        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
        if (!position) {// 沒(méi)有高亮選擇的字，則對(duì)已輸入的文字進(jìn)行字?jǐn)?shù)統(tǒng)計(jì)和限制
            if (toBeString.length > kMaxLength) {
                textField.text = [toBeString substringToIndex:kMaxLength];
                [self showTextView:self.view message:[NSString stringWithFormat:@"最多可輸入%ld位",(long)kMaxLength]];
            }
        }
        else{//有高亮選擇的字符串，則暫不對(duì)文字進(jìn)行統(tǒng)計(jì)和限制
        }
    }else{//中文輸入法以外的直接對(duì)其統(tǒng)計(jì)限制即可，不考慮其他語(yǔ)種情況
        if (toBeString.length > kMaxLength) {
            textField.text = [toBeString substringToIndex:kMaxLength];
            [self showTextView:self.view message:[NSString stringWithFormat:@"最多可輸入%ld位",(long)kMaxLength]];
        }
    }
}


#pragma mark - TextView Delegate

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
    if ([text isEqualToString:@"\n"]){ //判斷輸入的字是否是回車，即按下return
        //在這里做你響應(yīng)return鍵的代碼
        [self.view endEditing:YES];
        return NO; //這里返回NO，就代表return鍵值失效，即頁(yè)面上按下return，不會(huì)出現(xiàn)換行，如果為yes，則輸入頁(yè)面會(huì)換行
    }
    return YES;
}

- (void)textViewDidBeginEditing:(UITextView *)textView
{
    [UIView animateWithDuration:0.2 animations:^{
        _scrollView.contentOffset = CGPointMake(0, 70);
    }];
    
    //粗略的給textView加上placeholder
    if([textView.text isEqualToString:@"地址"]){
        textView.text=@"";
        textView.textColor = MakeColorRGB(0x7a8fac);
    }
}

- (void)textViewDidChange:(UITextView *)textView
{
    NSInteger kMaxLength = 200 ;
    NSString *toBeString = textView.text;
    NSString *lang = [[UIApplication sharedApplication]textInputMode].primaryLanguage; //ios7之前使用[UITextInputMode currentInputMode].primaryLanguage
    if ([lang isEqualToString:@"zh-Hans"]) { //中文輸入
        UITextRange *selectedRange = [textView markedTextRange];
        //獲取高亮部分
        UITextPosition *position = [textView positionFromPosition:selectedRange.start offset:0];
        if (!position) {// 沒(méi)有高亮選擇的字，則對(duì)已輸入的文字進(jìn)行字?jǐn)?shù)統(tǒng)計(jì)和限制
            if (toBeString.length > kMaxLength) {
                textView.text = [toBeString substringToIndex:kMaxLength];
            [self showTextView:self.view message:[NSString stringWithFormat:@"最多可輸入%ld位",(long)kMaxLength]];
            }
        }
        else{//有高亮選擇的字符串，則暫不對(duì)文字進(jìn)行統(tǒng)計(jì)和限制
        }
    }else{//中文輸入法以外的直接對(duì)其統(tǒng)計(jì)限制即可，不考慮其他語(yǔ)種情況
        if (toBeString.length > kMaxLength) {
            textView.text = [toBeString substringToIndex:kMaxLength];
            [self showTextView:self.view message:[NSString stringWithFormat:@"最多可輸入%ld位",(long)kMaxLength]];
        }
    }
}