Question

我想限制UITextField只接受一个小数点。

小数点前后最多允许3位数＆amp;小数点后最多允许2位数。

请注意，最小数字可以是1，小数不能输入第一个。

我怎样才能实现它？

Answer 1

您可以在同一场景中使用以下代码。

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{
NSString *expression = @"^([0-9]*)(\\.([0-9]+)?)?$";

    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression options:NSRegularExpressionCaseInsensitive error:nil];
    NSUInteger noOfMatches = [regex numberOfMatchesInString:newStr options:0 range:NSMakeRange(0,[newStr length])];

    if (noOfMatches==0)
    {
        return NO;
    }

NSUInteger newLength = [textField.text length] + [string length] - range.length;
    if(range.length + range.location > textField.text.length)
    {
        return NO;
    }
    if ([newStr containsString:@"."])
    {
        return newLength <= 6;
    }
    return newLength <= 3;

    //  return YES;
}

由于.被视为一个角色。总共将是6个字符。您可以在条件中调整值。

Answer 2

这是使用 Swift 和正则表达式实现它的方法：

设置文本字段的委托。这可以通过代码或IB来完成。

要验证用户输入的文本，您可以将代码添加到您的代理中，类似于以下内容：

// Number of digits that are allowed before decimal point
let kMaximumIntegerDigits = 3
// Number of digits that are allowed after decimal point
let kMaximumFractionDigits = 2

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

// The replacement string is empty when the user have removed some characters.
if string.isEmpty == true { return true }

// Get the current string the text field holds.
let currentText = textField.text ?? ""

// Check the limits.
if (string.characters.count + currentText.characters.count) > 6 { return false }

// Get the string we are expecting to obtain after the replacement.
var resultingText = currentText
resultingText.insertContentsOf(string.characters, at: currentText.startIndex.advancedBy(range.location))

// Check the final string with the help of the regular expression.
let regex = "^(?:(?:[0-9]{1,\(kMaximumIntegerDigits)}[.][0-9]{0,\(kMaximumFractionDigits)})|(?:[0-9]){1,\(kMaximumIntegerDigits)})$"
let regexRange = resultingText.rangeOfString(regex, options: .RegularExpressionSearch)
if regexRange == nil { return false }

return true

}

最后，您应该在用户尝试结束编辑会话时验证生成的文本。你可以这样做：

func textFieldShouldEndEditing(textField: UITextField) -> Bool {
 // Get the current input string.
 guard let currentText = textField.text else { return false }

 // Create the regular expression for the final check.
 let regex = "^(?:(?:[0-9]{1,\(kMaximumIntegerDigits)}[.][0-9]{1,\(kMaximumFractionDigits)})|(?:[0-9]){1,\(kMaximumIntegerDigits)})$"
 let regexRange = currentText.rangeOfString(regex, options: .RegularExpressionSearch)
 if regexRange == nil { 
 // Show an alert to the user with the message that explains what the input is expected...
 return false 
 }

 // Make additional clean-up and finalize the editing session.
 return true
}

Answer 3

非常感谢所有人的帮助。通过引用这些答案，我在下面给出了答案。

修改

虽然文本字段具有例如462.＆amp;用户将退格结果触及462，理想情况下应该导致46

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { NSString *strTextField = [textField.text stringByReplacingCharactersInRange:range withString:string]; // restrict textfield from entering ./0 at first place if (strTextField.length > 0) { NSString *theCharacterAtIndex0 = [NSString stringWithFormat:@"%c", [strTextField characterAtIndex:0]]; if ([theCharacterAtIndex0 isEqualToString:@"."] || [theCharacterAtIndex0 isEqualToString:@"0"]) { return NO; } } // NSLog(@"%@ , %@", textField.text, strTextField); // automatically add decimal point after 3 digits entered if (![textField.text containsString:@"."]) { if (strTextField.length == MAX_LENGTH_BeforeDecimal && ![strTextField containsString:@"."]) { strTextField = [strTextField stringByAppendingString:@"."]; textField.text = strTextField; return NO; } } // when decimal is deleted if ([textField.text containsString:@"."]) { if (![strTextField containsString:@"."]) { int indeOfdecimal = (int)[textField.text rangeOfString:@"."].location; NSString *strBeforeDecimal = [textField.text substringToIndex:indeOfdecimal]; textField.text = strBeforeDecimal; } } NSArray *separator = [strTextField componentsSeparatedByString:@"."]; // to restrict textfield to single decimal if([separator count] > 2 ) { return NO; } if([separator count] >= 2) { // restrict the max digits before & after decimal points NSString *sepStr0 = [NSString stringWithFormat:@"%@",[separator objectAtIndex:0]]; NSString *sepStr1 = [NSString stringWithFormat:@"%@",[separator objectAtIndex:1]]; if ([sepStr0 length] > 3) { return NO; } if ([sepStr1 length] > 2) { return NO; } } return YES; }

Answer 4

使用此正则表达式代码：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
   // Only allow one decimal point and 2 digits after it
   NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
   NSString *expression = @"^[0-9]{0,3}$*((\\.|,)[0-9]{0,2})?$";
   NSError *error = nil;
   NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression options:NSRegularExpressionCaseInsensitive error:&error];
   NSUInteger numberOfMatches = [regex numberOfMatchesInString:newString options:0 range:NSMakeRange(0, [newString length])];
   return numberOfMatches != 0;
   return YES;
 }

此处使用的正则表达式为“ ^ [0-9] {0， 3 } $ *（（\。|，）[0-9] {0， 2 }）？$“。

数字3（第一个粗体）表示小数点前的字符，数字2（第二个粗体）表示小数点后的字符。

您可以使用此正则表达式并根据需要创建规则。

Answer 5

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

// iPad Validations for Number only

NSCharacterSet *characterSet = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789."] invertedSet];

NSString *filteredString = [[string componentsSeparatedByCharactersInSet:characterSet] componentsJoinedByString:@""];

if (![string isEqualToString:filteredString]) {
    return NO;
}
  // HERE WRITE CODE FOR VALIDATION TO ALLOW CHARACTER AFTER "." 
 return YES;

}

UITextField只接受一个小数点，小数点前最多3位数＆amp;小数点后最多2位数

5 个答案: