只允许为UITextField输入数字(Allow only Numbers for UITextF

2019-06-18 13:37发布

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而iPad没有一个“小键盘”键盘像iPhone / iPod的一样。

我希望找到我如何可以限制用户的键盘只能通过9接受值0。

我可以想象使用的UITextField的“shouldChangeCharactersInRange”但我不知道要实现它的最好办法。

Answer 1:

这是我如何处理在SSN验证领域的问题，你可以修改的最大长度和删除if语句键盘类型检查，如果你需要。

还有逻辑以抑制当相对于粘贴数据用户正在键入的最大长度的警报。

在这种代码的情况下， BasicAlert()是一个#define宏，简单地示出了UIAlertView或UIAlertController使用传递的标题和消息字符串。 

// NOTE: This code assumes you have set the UITextField(s)'s delegate property to the object that will contain this code, because otherwise it would never be called.
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // allow backspace
    if (!string.length)
    {
        return YES;
    }

    // Prevent invalid character input, if keyboard is numberpad
    if (textField.keyboardType == UIKeyboardTypeNumberPad)
    {
        if ([string rangeOfCharacterFromSet:[NSCharacterSet decimalDigitCharacterSet].invertedSet].location != NSNotFound)
        {
            // BasicAlert(@"", @"This field accepts only numeric entries.");
            return NO;
        }
    }

    // verify max length has not been exceeded
    NSString *proposedText = [textField.text stringByReplacingCharactersInRange:range withString:string];

    if (proposedText.length > 4) // 4 was chosen for SSN verification
    {
        // suppress the max length message only when the user is typing
        // easy: pasted data has a length greater than 1; who copy/pastes one character?
        if (string.length > 1)
        {
            // BasicAlert(@"", @"This field accepts a maximum of 4 characters.");
        }

        return NO;
    }

    // only enable the OK/submit button if they have entered all numbers for the last four of their SSN (prevents early submissions/trips to authentication server)
    self.answerButton.enabled = (proposedText.length == 4);

    return YES;
}


Answer 2:

您可以使用此代码，允许在文本框只数。

该集合委托文本框之前

      textFieldName.delegate=self;

要么

      [textFieldName setDelegate:self];

比起使用此代码只允许一位数字文本框

      - (BOOL) textField: (UITextField *)theTextField shouldChangeCharactersInRange:(NSRange)range replacementString: (NSString *)string {
//return yes or no after comparing the characters

      // allow backspace
      if (!string.length)
      {
           return YES;
      }

      ////for Decimal value start//////This code use use for allowing single decimal value
      //    if ([theTextField.text rangeOfString:@"."].location == NSNotFound)
      //    {
      //        if ([string isEqualToString:@"."]) {
      //            return YES;
      //        }
      //    }
      //    else
      //    {
      //        if ([[theTextField.text substringFromIndex:[theTextField.text rangeOfString:@"."].location] length]>2)   // this allow 2 digit after decimal 
      //        {
      //            return NO;
      //        }
      //    }
      ////for Decimal value End//////This code use use for allowing single decimal value

      // allow digit 0 to 9
      if ([string intValue])
      {
            return YES;
      }

      return NO;
    }


Answer 3:

雨燕为代码非常具体的步骤

你可以提供限制在文本字段的输入逻辑func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool方法通过实现UITextFieldDelegate协议。

为了清楚起见，这些步骤假定您的故事板包含文本字段对象应该只接受数字的视图控制器 。

  1. 创建一个扩展视图控制器的自定义类UIViewController 。 请确保你的故事板现场通过设置在Xcode的身份检查的自定义类值指的是自定义类。 

     import UIKit class YourCustomController: UIViewController { override func viewDidLoad() { super.viewDidLoad() } }

  2. 创建从场景中的文本字段的插座，您的自定义视图控制器。 

     class YourCustomController: UIViewController { @IBOutlet weak var numberField: UITextField! ... }

  3. 应用UITextFieldDelegate在您的自定义视图控制器协议。 

     class YourCustomController: UIViewController, UITextFieldDelegate { ... }

  4. 在您的自定义视图控制器viewDidLoad方法，分配您的文本字段的委托到您的自定义视图控制器类。 

     override func viewDidLoad() { super.viewDidLoad() numberField.delegate = self }

  5. 添加UITextFieldDelegate的func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool方法。

    作为使自定义视图控制器的结果numberField的代表在先前步骤中，此方法将被每个用户输入的字符到文本字段中的时间调用。 如果你的方法返回true ，则角色将留在文本字段。 如果你的方法返回false则字符不会留在文本字段中。

    该string参数是由用户输入的字符。 如果string字符可以被转换成一个Int那么它是0和9之间; 否则，它是一些非数字字符。 

     class YourCustomController: UIViewController, UITextFieldDelegate { ... func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool { return Int(string) != nil } }

（见下面的全视图控制器代码）。

例如视图控制器与数字只有文本字段 

import UIKit

class YourCustomController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var numberField: UITextField!

    override func viewDidLoad() {        
        super.viewDidLoad()       
        numberField.delegate = self
    }

    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {        
        return Int(string) != nil
    }    
}

例如视图控制器与十进制文本字段

如果你想支持十进制数再利用的NSNumberFormatter 。 见差异的代码注释。 

import UIKit

class YourCustomController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var numberField: UITextField!

    private var formatter: NSNumberFormatter!

    override func viewDidLoad() {        
        super.viewDidLoad()       
        numberField.delegate = self

        // Initialize the formatter; minimum value is set to zero; style is Decimal. 
        formatter = NSNumberFormatter()
        formatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
        formatter.minimum = 0
    }

    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
        // Combine the current text field value and the new string
        // character. If it conforms to the formatter's settings then
        // it is valid. If it doesn't then nil is returned and the
        // string character should not be allowed in the text field.         
        return formatter.numberFromString("\(textField.text)\(string)") != nil
    }    
}


Answer 4:

试试这个，以避免文本框结算问题

雨燕3.0 

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    guard NSCharacterSet(charactersInString: "0123456789").isSupersetOfSet(NSCharacterSet(charactersInString: string)) else {
        return false
    }
    return true
}

雨燕4.0 

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard CharacterSet(charactersIn: "0123456789").isSuperset(of: CharacterSet(charactersIn: string)) else {
        return false
    }
    return true
}


Answer 5:

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

    NSNumberFormatter * nf = [[NSNumberFormatter alloc] init];
    [nf setNumberStyle:NSNumberFormatterNoStyle];

    NSString * newString = [NSString stringWithFormat:@"%@%@",textField.text,string];
    NSNumber * number = [nf numberFromString:newString];

    if (number)
        return YES;
    else
       return NO;
}


Answer 6:

我应用这个和它的作品！ 

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
// Check for non-numeric characters
NSUInteger lengthOfString = string.length;
for (NSInteger index = 0; index < lengthOfString; index++) {
    unichar character = [string characterAtIndex:index];
    if (character < 48) return NO; // 48 unichar for 0
    if (character > 57) return NO; // 57 unichar for 9
}
// Check total length for restrict user
NSUInteger proposedNewLength = textField.text.length - range.length + string.length;
if (proposedNewLength > 6)
    return YES;
return YES;                                                                                                                                     
}


Answer 7:

NSString* val = [[textField text] stringByReplacingCharactersInRange:range withString:string];
    NSCharacterSet *allowedCharacterSet = [NSCharacterSet decimalDigitCharacterSet];
    if ([[string componentsSeparatedByCharactersInSet:[allowedCharacterSet invertedSet]] count] > 1 || [val length] > 5) {
        return NO;
    }


Answer 8:

Works fine for me :

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (([string rangeOfCharacterFromSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]].location != NSNotFound) && !(range.length==1 && string.length==0)) {
            return NO;
        }
        return YES;
    }


Answer 9:

从内部表示保持鲜明的呈现数据。 还有一个更简单的方法。 让NSNumberFormatter做的工作： 

 NSNumberFormatter* ns = [[NSNumberFormatter alloc] init];
 ns.numberStyle = NSNumberFormatterDecimalStyle;
 [ns setMaximumFractionDigits:2];
 // This is your internal representation of the localized number
 double a = [[ns numberFromString:self.textIVA.text] doubleValue]];

[mylabel setText:[NSString stringWithFormat:@"€ %@",
     [NSNumberFormatter localizedStringFromNumber:
                          [NSNumber numberWithDouble:a]
                                      numberStyle:NSNumberFormatterDecimalStyle]]];


Answer 10:

如果你用我的规范模式则代码如下所示

textField.delegate = self

lazy var specification: Specification = {
    return RegularExpressionSpecification(pattern: "^(|0|[1-9]\\d{0,6})$")
}()

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let textFieldString: NSString = textField.text ?? ""
    let s = textFieldString.stringByReplacingCharactersInRange(range, withString:string)
    return specification.isSatisfiedBy(s)
}

func textFieldShouldReturn(textField: UITextField) -> Bool {
    let s = textField.text ?? ""
    let isTextValid = specification.isSatisfiedBy(s)
    if isTextValid {
        textField.resignFirstResponder()
    }
    return false
}


Answer 11:

我已经修改@ IDEV的回答为七段工作和“”： 

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
     // Check for non-numeric characters
     NSUInteger lengthOfString = string.length;
     for (NSInteger index = 0; index < lengthOfString; index++) {
         unichar character = [string characterAtIndex:index];
         if ((character < 48) && (character != 46)) return NO; 
         // 48 unichar for 0, and 46 unichar for point
         if (character > 57) return NO; 
         // 57 unichar for 9
     }
     // Check for total length
     NSUInteger proposedNewLength = textField.text.length - range.length + string.length;
     if (proposedNewLength > 6)
         return YES;
     return YES; 
 }


Answer 12:

SWIFT 3 

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField==yourTextFieldOutlet {
                if(CharacterSet.decimalDigits.isSuperset(of: CharacterSet(charactersIn: yourTextFieldOutlet.text!))){
//if numbers only, then your code here
                }
                else{
                showAlert(title: "Error",message: "Enter Number only",type: "failure")
                }
            }
    return true
    }


Answer 13:

使用此代码： 

NSString* val = [[textField text] stringByReplacingCharactersInRange:range withString:string];
NSCharacterSet *allowedCharacterSet = [NSCharacterSet decimalDigitCharacterSet];
if ([[string componentsSeparatedByCharactersInSet:[allowedCharacterSet invertedSet]] count] > 1 || [val length] > 5) {
    return NO;
}


文章来源: Allow only Numbers for UITextField input
标签： ios ipad cocoa-touch uitextfield uikeyboard
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