如何限制UITextField中的小數點數？

Question

我有一個UITextField，點擊時在左下角出現一個帶有小數點的數字鍵盤。我正在嘗試限制該字段，以便用戶只能放置1個小數點。例如，
2.5 OK
2..5 NOT OK

Answer 1

貫徹shouldChangeCharactersInRange方法是這樣的：

// Only allow one decimal point 
// Example assumes ARC - Implement proper memory management if not using. 
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string]; 
    NSArray *arrayOfString = [newString componentsSeparatedByString:@"."]; 

    if ([arrayOfString count] > 2) 
     return NO; 

    return YES; 
} 

這產生由小數點分割字符串數組，所以如果有一個以上的小數點我們將有陣列中的至少3個元素。

Answer 2

在任何物體您設置的UITextField的委託，添加解答了"[- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string]"的方法。

然後，您可以使用NSNumberFormatter對象，也可以蠻力檢查已存在的小數位標記（如果小數標記已存在，則返回NO）。

Answer 3

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    if(textField == min_textfield) 
    { 
     if([textField.text rangeOfString:@"."].location == NSNotFound) 
     { 
      if([string isEqualToString:@"."]) 
      { 
       flag_for_text = 1; 
      } 
      else 
      { 
       textField.text = [NSMutableString stringWithFormat:@"%@",textField.text]; 
      } 
     } 
     else 
     { 
      if([string isEqualToString:@"."]) 
      { 
       return NO; 
      } 
      else 
      { 
       textField.text = [NSMutableString stringWithFormat:@"%@",textField.text]; 
      } 
     } 
    } 
} 

Answer 4

簡而言之，數字格式如下[NSString stringWithFormat:@"%9.5f", x];其中5是「，」後面的小數。

Answer 5

下面是一個正則表達式的例子，該例子僅限於一個小數點和2個小數點。您可以調整它以適應您的需求。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { 
    NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string]; 
    NSString *expression = @"^[0-9]*((\\.|,)[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; 
} 

Answer 6

大廈接受的答案，下面的方法確認3例錢格式處理時很有用：

1. 極大量小數點後
2. 超過200個字符
3. 超過1小數點

請確保您的文本字段的del egate設置正確，你的類符合UITextField協議，並添加下面的委託方法。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    // Check for deletion of the $ sign 
    if (range.location == 0 && [textField.text hasPrefix:@"$"]) 
    return NO; 

    NSString *updatedText = [textField.text stringByReplacingCharactersInRange:range withString:string]; 
    NSArray *stringsArray = [updatedText componentsSeparatedByString:@"."]; 

    // Check for an absurdly large amount 
    if (stringsArray.count > 0) 
    { 
    NSString *dollarAmount = stringsArray[0]; 
    if (dollarAmount.length > 6) 
     return NO; 
    } 

    // Check for more than 2 chars after the decimal point 
    if (stringsArray.count > 1) 
    { 
    NSString *centAmount = stringsArray[1]; 
    if (centAmount.length > 2) 
     return NO; 
    } 

    // Check for a second decimal point 
    if (stringsArray.count > 2) 
    return NO; 

    return YES; 
} 

Answer 7

我做出瞭解決方案，爲您帶來控制小數計算，所以用戶可以鍵入只有一個小數點分隔符，你也可以有超過小數的控制數。

只需設置decimalPlacesLimit正確的值。

查看方法：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    NSLog(@"text on the way: %@", string); 
    NSUInteger decimalPlacesLimit = 2; 

    NSRange rangeDot = [textField.text rangeOfString:@"." options:NSCaseInsensitiveSearch]; 
    NSRange rangeComma = [textField.text rangeOfString:@"," options:NSCaseInsensitiveSearch]; 
    if (rangeDot.length > 0 || rangeComma.length > 0){ 
     if([string isEqualToString:@"."]) { 
      NSLog(@"textField already contains a separator"); 
      return NO; 
     } else { 
      NSArray *explodedString = [textField.text componentsSeparatedByString:@"."]; 
      NSString *decimalPart = explodedString[1]; 
      if (decimalPart.length >= decimalPlacesLimit && ![string isEqualToString:@""]) { 
       NSLog(@"textField already contains %d decimal places", decimalPlacesLimit); 
       return NO; 
      } 
     } 
    } 

    return YES; 
} 

Answer 8

試試這個： -

public func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool { 

    if(text == "," || text == "."){ 
     let countdots = textView.text!.componentsSeparatedByString(".").count - 1 

     if countdots > 0 && (text == "." || text == ",") 
     { 
      return false 
     } 
    } 

    return true 
} 

Answer 9

爲SWIFT 2。3，防止用戶對後兩個地方輸入十進制數 -

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool 
{ 
    let decimalPlacesLimit = 2 
    let rangeDot = txtPrice.text!.rangeOfString(".", options: .CaseInsensitiveSearch) 

    if rangeDot?.count > 0 
    { 
     if (string == ".") 
     { 
      print("textField already contains a separator") 
      return false 
     } 
     else { 

      var explodedString = txtPrice.text!.componentsSeparatedByString(".") 
      let decimalPart = explodedString[1] 
      if decimalPart.characters.count >= decimalPlacesLimit && !(string == "") 
      { 
       print("textField already contains \(decimalPlacesLimit) decimal places") 
       return false 
      } 
     } 
    } 
} 

Answer 10

斯威夫特3

無需創建一個數組，並檢查計數。限制用戶只能像這樣放置1個小數點。

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { 
    if (textField.text?.contains("."))! && string.contains(".") 
    { 
     return false 
    } 
    else 
    { 
     return true 
    } 
} 

Answer 11

夫特3實現此UITextFieldDelegate方法，以防止用戶從輸入的數字無效：

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { 
    let text = (textField.text ?? "") as NSString 
    let newText = text.replacingCharacters(in: range, with: string) 
    if let regex = try? NSRegularExpression(pattern: "^[0-9]*((\\.|,)[0-9]*)?$", options: .caseInsensitive) { 
     return regex.numberOfMatches(in: newText, options: .reportProgress, range: NSRange(location: 0, length: (newText as NSString).length)) > 0 
    } 
    return false 
} 

它正與兩個逗號或點爲十進制分隔符。您還可以使用此模式限制小數位數："^[0-9]*((\\.|,)[0-9]{0,2})?$"（在本例中爲2）。