Ios 如何限制UITextField中的小数点数量？

我有一个UITextField，当单击它时，会显示一个左下角有小数点的数字键盘。我试图限制该字段，以便用户只能放置1个小数点

e、 g.
2.5正常

---

2..5不正常

在将UITextField的委托设置为的任何对象中，添加一个响应的方法

---

然后，您可以使用

NSNumberFormatter

对象，也可以强制检查已存在的小数点标记（如果已存在小数点标记，则返回

NO

）

实现shouldChangeCharactersRange方法，如下所示：

// 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;
}

---

这将创建一个按小数点拆分的字符串数组，因此如果有多个小数点，则数组中至少有3个元素。

简而言之，数字格式如下

[NSString stringWithFormat:@“%9.5f”，x]其中5是“，”之后的小数点
这里是一个正则表达式示例，该示例仅限于一个小数点和两个小数点。你可以调整它以满足你的需要

-(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];
            }
        }
    }
}

- (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;
}

在公认答案的基础上，以下方法验证了在处理货币格式时有帮助的三种情况：

极大量
小数点后超过2个字符
超过1个小数点
确保文本字段的委托设置正确，类符合
UITextField
协议，并添加以下委托方法

- (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;
}

我提出了一个解决方案，它可以控制小数点计数，所以用户只能键入一个小数点分隔符，还可以控制小数点计数

只需正确设置小数点值即可

参见方法：

- (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;
}

试试这个：-

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
}

用于Swift 2.3，以防止用户在两位之后输入十进制数字-

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
            }
        }
    }
}

Swift 3

无需创建数组和检查计数。限制用户只能像这样放置1个小数点

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

Swift 3实现此UITextFieldDelegate方法以防止用户键入无效数字：

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
}

它使用逗号或点作为十进制分隔符。您还可以使用以下模式限制分数位数：
“^[0-9]*（（\\.\124；，）[0-9]{0,2}）？$”
（在本例中为2）。
Swift 4

在UITextField中避免多个小数点（.or，）的高效简便方法：

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if(string == "," || string == "." ){

        if ((textField.text?.contains(","))! || (textField.text?.contains("."))!){
            return false
        }
    }
    return true
}

斯威夫特4
func textField（textField:UITextField，shouldChangeCharacters范围：NSRange，replacementString:string）->Bool{
//允许删除字符（退格）
如果字符串==“”{
返回真值
}
//块多点
if（textField.text？.contains（“.”）！&&string==”{
返回错误
}
//请勾选这里的小数位
如果（textField.text？.contains（“.”）{
设limitDecimalPlace=2
设decimalPlace=textField.text？.components（以“.”分隔）。最后
如果（小数点？.count）！

目标-C
//在.h文件或.m文件中创建此变量
浮点数；
//在viewDidLoad方法中赋值
numberOfDecimal=2；
#pragma标记-TextFieldDelegate
-（BOOL）textField:（UITextField*）textField应更改字符范围：（NSRange）范围替换字符串：（NSString*）字符串{
//允许删除字符（退格）
if（[string IsequalString:@”“）{
返回true；
}
//块多点
if（[textField.text containssString:@.”）和&[string IsequalString:@.”）{
返回false；
}
//请勾选这里的小数位
if（[textField.text包含字符串：@”。））{
NSString*strDecimalPlace=[[textField.text componentsSeparatedByString:@.'']lastObject]；
if（strDecimalPlace.length<\u numberOfDecimal）{
返回true；
}
否则{
返回false；
}
}
返回true；
}
Swift 4

最大整数数为4，即9999，最大小数位数限制为2。所以，最大数字可以是9999.99

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


    // 100 is the tag value of our textfield
    /*or you may use "if textfield == myTextField{" if you have an IBOutlet to that textfield */
    if textField.tag == 100 {

        //max length limit of text is 8
        if textField.text!.count > 8 && string != "" {
            return false
        }

        let maxLength = 8
        let currentString: NSString = textField.text! as NSString 

//如果您正在向该文本字段输入价格，并且希望在用户开始在该文本字段中键入时在开始时自动插入$，请使用以下代码，或者您可以在开始处放置其他字符，而不是$。否则，请注释以下3行if条件代码

        if currentString.length == 0 {
            priceTextField.text = "$"
        }

//插入新输入的字符后的新字符串

        let newString: NSString =
            currentString.replacingCharacters(in: range, with: string) as NSString


        if newString.length > maxLength{
            return false
        }

        if (textField.text!.range(of: ".") != nil) {
            let numStr = newString.components(separatedBy: ".")
            if numStr.count>1{
                let decStr = numStr[1]
                if decStr.length > 2{
                    return false
                }
            }
        }

        var priceStr: String = newString as String

        if (textField.text!.range(of: "$") != nil) {
            priceStr = priceStr.replacingOccurrences(of: "$", with: "")
        }

        let price: Double = Double(priceStr) ?? 0

        if price > 9999.99{
            return false
        }

        switch string {
        case "0","1","2","3","4","5","6","7","8","9":
            return true
        case ".":
            let array = Array(textField.text!)
            var decimalCount = 0
            for character in array {
                if character == "." {
                    decimalCount = decimalCount + 1
                }
            }

            if decimalCount == 1 {
                return false
            } else {
                return true
            }
        default:

            let array = Array(string)
            if array.count == 0 {
                return true
            }
            return false
        }
    }
    return true
}

如果文本字段文本已包含“.”，则返回否，否则返回是。
SWIFT 5
改进

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    //!\ set the keyboard type to : Decimal Pad /!\\
    // CUSTOM SETUP
    let c = NSLocale.current.decimalSeparator ?? "."
    let limitBeforeSeparator = 2
    let limitAfterSeparator = 2
    // ---------
    
    
    var validatorUserInput:Bool = false
    
    let text = (textField.text ?? "") as NSString
    let newText = text.replacingCharacters(in: range, with: string)
    
    
    // Validator
    let pattern = "(?!0[0-9])\\d*(?!\\\(c))^[0-9]{0,\(limitBeforeSeparator)}((\\\(c))[0-9]{0,\(limitAfterSeparator)})?$"
    if let regex = try? NSRegularExpression(pattern: pattern, options: .caseInsensitive) {
        validatorUserInput = regex.numberOfMatches(in: newText, options: .reportProgress, range: NSRange(location: 0, length: (newText as NSString).length)) > 0
    }
     
    
    if validatorUserInput {
        // setting data or something eles before the return
        if let char = string.cString(using: String.Encoding.utf8) {
            let isBackSpace = strcmp(char, "\\b")
            if (isBackSpace == -92 && textField.text?.count == 1) {
                print("Backspace was pressed")
                print(newText)
                // do something...
                
            } else {
                print("Number Added")
                print(newText)
                // do something...
                
            }
        }
        return validatorUserInput
    } else {
        return validatorUserInput
    }
}

信息：不允许：


开头的分隔符
零加上开始处的另一个数字，除非在后面添加分隔符

1：将键盘类型设置为：十进制键盘


2：复制过去的内容

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    //!\ set the keyboard type to : Decimal Pad /!\\
    // CUSTOM SETUP
    let c = NSLocale.current.decimalSeparator ?? "."
    let limitBeforeSeparator = 2
    let limitAfterSeparator = 2
    // ---------
    
    
    var validatorUserInput:Bool = false
    
    let text = (textField.text ?? "") as NSString
    let newText = text.replacingCharacters(in: range, with: string)
    
    
    // Validator
    let pattern = "(?!0[0-9])\\d*(?!\\\(c))^[0-9]{0,\(limitBeforeSeparator)}((\\\(c))[0-9]{0,\(limitAfterSeparator)})?$"
    if let regex = try? NSRegularExpression(pattern: pattern, options: .caseInsensitive) {
        validatorUserInput = regex.numberOfMatches(in: newText, options: .reportProgress, range: NSRange(location: 0, length: (newText as NSString).length)) > 0
    }
     
    
    if validatorUserInput {
        // setting data or something eles before the return
        if let char = string.cString(using: String.Encoding.utf8) {
            let isBackSpace = strcmp(char, "\\b")
            if (isBackSpace == -92 && textField.text?.count == 1) {
                print("Backspace was pressed")
                print(newText)
                // do something...
                
            } else {
                print("Number Added")
                print(newText)
                // do something...
                
            }
        }
        return validatorUserInput
    } else {
        return validatorUserInput
    }
}

3：如果要在分隔符前后设置x个最大位数，请在方法中设置

 let limitBeforeSeparator = 2 
 let limitAfterSeparator = 2

您可以使用NSRegularExpression来确定新闻字符串是否包含多个十进制数，而不是使用componentsSeparatedByString。真！有很多方法可以做到这一点。我通常使用它是因为我经常想对整数和小数部分做一些不同的事情。使用正则表达式可以更好地控制textfield接受的字符以及它们将采用的格式。@nizx对于这种特定情况，我认为这并不重要，尽管您的示例较长且“看起来”对于新用户来说更复杂。对于更复杂的示例，您很可能是对的，或者如果它们是数字，那么使用NSNumberFormatter也可能是合适的。对于十进制分隔符，您也可以从[[NSLocale currentLocale]objectForKey:NSLocaleEdecimalSeparator]]获得它，而不是@“.”。这样，代码也可以正确地用于usi区域
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    //!\ set the keyboard type to : Decimal Pad /!\\
    // CUSTOM SETUP
    let c = NSLocale.current.decimalSeparator ?? "."
    let limitBeforeSeparator = 2
    let limitAfterSeparator = 2
    // ---------
    
    
    var validatorUserInput:Bool = false
    
    let text = (textField.text ?? "") as NSString
    let newText = text.replacingCharacters(in: range, with: string)
    
    
    // Validator
    let pattern = "(?!0[0-9])\\d*(?!\\\(c))^[0-9]{0,\(limitBeforeSeparator)}((\\\(c))[0-9]{0,\(limitAfterSeparator)})?$"
    if let regex = try? NSRegularExpression(pattern: pattern, options: .caseInsensitive) {
        validatorUserInput = regex.numberOfMatches(in: newText, options: .reportProgress, range: NSRange(location: 0, length: (newText as NSString).length)) > 0
    }
     
    
    if validatorUserInput {
        // setting data or something eles before the return
        if let char = string.cString(using: String.Encoding.utf8) {
            let isBackSpace = strcmp(char, "\\b")
            if (isBackSpace == -92 && textField.text?.count == 1) {
                print("Backspace was pressed")
                print(newText)
                // do something...
                
            } else {
                print("Number Added")
                print(newText)
                // do something...
                
            }
        }
        return validatorUserInput
    } else {
        return validatorUserInput
    }
}

 let limitBeforeSeparator = 2 
 let limitAfterSeparator = 2