ios - 将焦点转移到下一个文本字段

Question

我有一组 4 个文本字段。我对这些文本字段应用了一定的限制，下面的代码可以很容易地理解这些限制。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSString * newString = [textField.text stringByReplacingCharactersInRange:range withString:string];

    if (string.length==0) {
        return YES;
    }


    if (textField == txt_mins) {
        return [[AppDelegate sharedInstance] setNumberFormat:textField newString:newString
        IntegerLimit:5 FractionLimit:2 NumberType:2];
    }
    else if (textField == txt_units){
        return [[AppDelegate sharedInstance] setNumberFormat:textField newString:newString 
        IntegerLimit:5 FractionLimit:2 NumberType:2];
    }
    // Below logic is for All 4 Modifer Textfields
    // we are restricting the user to enter only max 2 characters in modifier textfields and
     also automatically
    // converting each entered character to the uppercase string.
    if (textField==txt_modifier1 || textField==txt_modifier2 || textField==txt_modifier3 ||
     textField==txt_modifier4) {
        // This condition is restricting the user from entering the special characters in the
        modifier textfield.
        if ([string rangeOfCharacterFromSet:[[NSCharacterSet alphanumericCharacterSet] 
        invertedSet]].location != NSNotFound) {
            // There are non-alphanumeric characters in the replacement string
            return NO;
        }
        else{
        NSString *result = [textField.text stringByReplacingCharactersInRange:range 
        withString:string.uppercaseString];
        if (result.length <= 2)
            textField.text = result;
        return NO;
       }
    }
    return YES;
}

我真正想要的是txt_modifier1。一旦我在文本字段中键入我的两个字符，焦点应该转移到下一个文本字段，即 txt_modifier2 并且对于其他修饰符文本字段也是如此。我在 shouldChangeCharactersInRange: 方法中做了这些限制。请在我的代码中提出处理这种增强的方法。

Answer 1

@property UIView *firstResponder;

- (void) toggleTextfield 
{
    NSInteger nextTag = self.firstResponder.tag;
    nextTag += 1;
    UITextField *nextTextField = (UITextField *)[self.view viewWithTag:nextTag];  
    if (nextTextField)  
    {  
        [nextTextField becomeFirstResponder];  
    }  
}  

将标签值分配给您想要使用的所有文本字段。
当你想转移焦点时调用这个方法。

添加这一行textFieldDidBeginEditing:

self.firstResponder = textField;

Replace this code 
if (result.length <= 2)
  textField.text = result  
return NO; 

with 

 if (result.length <= 2) 
        textField.text = result; 
    else [self toggleTextfield]; 

and add this function - 

(void)textFieldDidBeginEditienter code hereng:(UITextField *)textField   
{  
     self.firstResponder = textField;   
}

Answer 2

if (textField==txt_modifier1)
{
 // This condition is restricting the user from entering the special characters in the
    modifier textfield.
    if ([string rangeOfCharacterFromSet:[[NSCharacterSet alphanumericCharacterSet] 
    invertedSet]].location != NSNotFound) {
        // There are non-alphanumeric characters in the replacement string
        return NO;
    }
    else{
    NSString *result = [textField.text stringByReplacingCharactersInRange:range 
    withString:string.uppercaseString];
    if (result.length <= 2)
        textField.text = result;
    else
    [txt_modifier2 becomeFirstresponder];

    return NO;
   }
}
else if( textField==txt_modifier2 )
{
same code of above block just change the text filed on which you want to focus next
}
else if(textField==txt_modifier3 )
{
same code of above block just change the text filed on which you want to focus next
}
else if(textField==txt_modifier4) 
{
same code of above block just change the text filed on which you want to focus next
}

希望这对你有帮助。让我知道结果