Ios 如何在输入四个字符后写入UItextfield长度和更改键盘数字格式的条件

在Uitextfield中，长度为6，前四个字符必须是字符串，其余两个必须是数字，当我输入前四个字符时，我尝试输入第五个字符键盘更改为数字格式，那么我如何在目标c中写入上述条件。

可以使用其属性

键盘类型以编程方式更改键盘类型。由于您必须检查每个输入，您需要使用哪个键盘来实现
shouldChangeCharactersInRange
的委托方法
UITextFieldDelegate

- (BOOL)textField:(UITextField *)textField
shouldChangeCharactersInRange:(NSRange)range
replacementString:(NSString *)string
{

   // NSLog(@"%d",range);
 NSString * r = [NSString stringWithFormat:@"%d", range];
 NSLog(@"%@",r);
 if ([r  isEqual: @"4"])
 {
    [_txtView setKeyboardType:UIKeyboardTypeNumberPad];
    [self.view endEditing:YES];
    [_txtView becomeFirstResponder];

 }


 return YES;
}

下面是一个示例，您可以对其进行优化以减少重新加载的次数

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textfield == <Your texfield>) { // this condition is required in case of multiple textfields in the same view else you can skip
        NSString *finalString = [textField.text stringByReplacingCharactersInRange:range withString:string];
        if (finalString.length <= 6) {
            if (finalString.length > 3) {
                textField.keyboardType = UIKeyboardTypePhonePad;
            } else {
                textField.keyboardType = UIKeyboardTypeDefault;
            }
            [textField reloadInputViews];
        } else {
            return NO;
        }
    }
}

-（BOOL）textField:（UITextField*）textField应更改字符范围：（NSRange）范围替换字符串：（NSString*）字符串
{
如果（textfield==）{//如果同一视图中有多个textfield，则需要此条件，否则可以跳过
NSString*finalString=[textField.text stringByReplacingCharactersInRange:range with string:string]；
如果（最后一环长度3）{
textField.keyboardType=UIKeyboardTypePhonePad；
}否则{
textField.keyboardType=UIKeyboardTypeDefault；
}
[文本字段重新加载输入视图]；
}否则{
返回否；
}
}
}
func textField（\utextfield:UITextField，shouldChangeCharacters范围：NSRange，replacementString:string）->Bool

您可以使用此委托函数并根据需要添加所有必要的条件。下面我展示了一些示例通用代码。您还可以根据文本长度键入键盘

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool{


    //length condition and also trim the string before yu check for space and dot(.)
    if(textField.text?.characters.count == 6){
        return false
    }

    //alphabetic condition
    if((textField.text?.characters.count <= 4)){

        if(string == "number"){
            return false
        }
    }else if((textField.text?.characters.count > 4  )){
        if(string == "alphabetic"  ){
            return false
        }

    }

    return true
}

func textField（textField:UITextField，shouldChangeCharacters范围：NSRange，replacementString:string）->Bool{
//长度条件，并在检查空格和圆点之前修剪字符串（.）
if（textField.text？.characters.count==6）{
返回错误
}
//字母条件
如果（（textField.text？.characters.count 4））{
如果（字符串==“字母”）{
返回错误
}
}
返回真值
}
-（BOOL）textField:（UITextField*）textField应更改字符范围：（NSRange）范围替换字符串：（NSString*）字符串{
if（string.length==0）{
如果（textField.text.length==4）{
textField.keyboardType=UIKeyboardTypeDefault；
textField.resignFirstResponder；
textField.becomeFirstResponder；
}
}否则{
如果（textField.text.length==3）{
textField.keyboardType=UIKeyboardTypeNumberPad；
textField.resignFirstResponder；
textField.becomeFirstResponder；
返回否；
}如果（textField.text.length<4）{
NSCharacterSet*cs=[[NSCharacterSet characterSetWithCharactersInString:@“ABCDEFGHIJKLMNOPQRSTUVWXYZABCDFGHIJKLMNOPQRSTUVWXYZ”]逆变器集]；
NSString*筛选=[[string componentsSeparatedByCharactersInSet:cs]componentsJoinedByString:@”“]；
返回[字符串isEqualToString:已筛选]；
}else if（textField.text.length==6）{
返回YES；
}
}
返回true；

}

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (string.length == 0) {
    if (textField.text.length == 4) {
        textField.keyboardType = UIKeyboardTypeDefault;
        textField.resignFirstResponder;
        textField.becomeFirstResponder;
    }
} else {
    if (textField.text.length == 3) {
        textField.keyboardType = UIKeyboardTypeNumberPad;
        textField.resignFirstResponder;
        textField.becomeFirstResponder;
        return NO;
    } if (textField.text.length < 4) {
        NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"] invertedSet];
        NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
        return [string isEqualToString:filtered];
    } else if (textField.text.length == 6) {
        return YES;
    }
}

return true;