最近业务要求输入字母的同时必须强制大写，而且不能录入中文，点击提交的时候判断还不行，必须要求输入的同时判断匹配

- (void)textFieldChangeValue:(UITextField *)textfield{
    if ([[MBISingletonCacheData retrieveUserSegmentId] isEqualToString:@"91"]) {
        if ([[UITextInputMode currentInputMode].primaryLanguage isEqualToString:@"zh-Hans"]) {//这个方法在iOS 7 被废弃，但是可以使用
            return;
        }else{
            textfield.text = [textfield.text uppercaseString];
        }
    }
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if ((textField.tag == 666 || textField.tag == 777)&&[[MBISingletonCacheData retrieveUserSegmentId]isEqualToString:@"91"]) { // 判断输入框是当前需要判断控制的输入框
        NSCharacterSet *set = [[NSCharacterSet characterSetWithCharactersInString:ALPHA] invertedSet];
        NSString *filterd = [[string componentsSeparatedByCharactersInSet:set] componentsJoinedByString:@""];
        return [string isEqualToString:filterd];
    }
    return false;
}

ALPHA 使用宏定义写好 def ALPHA @"QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm 1234567890"