Restrict NSTextField to only allow numbers - cocoa

Question

How do I restrict a NSTextField to allow only numbers/integers? I've found questions like this one, but they didn't help!

Answer 1

Try to make your own NSNumberFormatter subclass and check the input value in -isPartialStringValid:newEditingString:errorDescription: method.
#interface OnlyIntegerValueFormatter : NSNumberFormatter
#end
#implementation OnlyIntegerValueFormatter
- (BOOL)isPartialStringValid:(NSString*)partialString newEditingString:(NSString**)newString errorDescription:(NSString**)error
{
if([partialString length] == 0) {
return YES;
}
NSScanner* scanner = [NSScanner scannerWithString:partialString];
if(!([scanner scanInt:0] && [scanner isAtEnd])) {
NSBeep();
return NO;
}
return YES;
}
#end
And then set this formatter to your NSTextField:
OnlyIntegerValueFormatter *formatter = [[[OnlyIntegerValueFormatter alloc] init] autorelease];
[textField setFormatter:formatter];

Answer 2

Swift 3 Version
import Foundation
class OnlyIntegerValueFormatter: NumberFormatter {
override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
// Ability to reset your field (otherwise you can't delete the content)
// You can check if the field is empty later
if partialString.isEmpty {
return true
}
// Optional: limit input length
/*
if partialString.characters.count>3 {
return false
}
*/
// Actual check
return Int(partialString) != nil
}
}
Use:
let onlyIntFormatter = OnlyIntegerValueFormatter()
myNsTextField.formatter = onlyIntFormatter

Answer 3

Here's a solution with filtering. Give a delegate and an outlet to textfield and set controlTextDidChange method.
- (void)controlTextDidChange:(NSNotification *)aNotification {
NSTextField *textfield = [notification object];
NSCharacterSet *charSet = [NSCharacterSet characterSetWithCharactersInString:#"0123456789"];
char *stringResult = malloc([textfield.stringValue length]);
int cpt=0;
for (int i = 0; i < [textfield.stringValue length]; i++) {
unichar c = [textfield.stringValue characterAtIndex:i];
if ([charSet characterIsMember:c]) {
stringResult[cpt]=c;
cpt++;
}
}
stringResult[cpt]='\0';
textfield.stringValue = [NSString stringWithUTF8String:stringResult];
free(stringResult);
}

Answer 4

Try this -
NSNumberFormatter *formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
[textField setFormatter:formatter];

Answer 5

Here is a Swift version:
override func isPartialStringValid(partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>) -> Bool {
if (count(partialString.utf16)) {
return true
}
if (partialString.rangeOfCharacterFromSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet) != nil) {
NSBeep()
return false
}
return true
}

Answer 6

In SWIFT, I do it this way
Convert the text value to Int with Int()
Check the converted value is not less than 0
If less than 0, display error message other accept the value
if ((Int(txtField.stringValue)) < 0){
// Display error message
}

Answer 7

[Works with Swift 3.0.1]
As others suggested, subclass NumberFormatter and override isPartialStringValid method. The easiest way is to drop a NumberFormatter object under your NSTextField in xib/storyboard and update it's Custom Class.
Next implementation allows only integers or blank value and plays a beep if string contains illegal characters.
class IntegerFormatter: NumberFormatter {
override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
// Allow blank value
if partialString.numberOfCharacters() == 0 {
return true
}
// Validate string if it's an int
if partialString.isInt() {
return true
} else {
NSBeep()
return false
}
}
}
String's numberOfCharacters() and isInt() are methods added in an extension.
extension String {
func isInt() -> Bool {
if let intValue = Int(self) {
if intValue >= 0 {
return true
}
}
return false
}
func numberOfCharacters() -> Int {
return self.characters.count
}
}

Answer 8

Here is the steps to create the same....
Just create the ANYCLASS(called SAMPLE) with sub classing the NSNumberFormatter ...
in .m file write the following code...
- (BOOL)isPartialStringValid:(NSString *)partialString newEditingString:(NSString **)newString errorDescription:(NSString **)error {
// Make sure we clear newString and error to ensure old values aren't being used
if (newString) { *newString = nil;}
if (error) {*error = nil;}
static NSCharacterSet *nonDecimalCharacters = nil;
if (nonDecimalCharacters == nil) {
nonDecimalCharacters = [[NSCharacterSet decimalDigitCharacterSet] invertedSet] ;
}
if ([partialString length] == 0) {
return YES; // The empty string is okay (the user might just be deleting everything and starting over)
} else if ([partialString rangeOfCharacterFromSet:nonDecimalCharacters].location != NSNotFound) {
return NO; // Non-decimal characters aren't cool!
}
return YES;
}
Now.. in your Actual Class set the formatter to your NSTextField object like below...
NSTextField *mySampleTxtFld;
for this set the Formatter...
SAMPLE* formatter=[[SAMPLE alloc]init];// create SAMPLE FORMATTER OBJECT
self.mySampleTxtFld.delegate=self;
[self.mySampleTxtFld setFormatter:formatter];
Your done!!!

Answer 9

Swift 2.0 custom formatter with 0 instead of empty space :
class OnlyIntegerValueFormatter: NSNumberFormatter {
override func isPartialStringValid(partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>) -> Bool {
if partialString.isEmpty {
newString.memory = "0"
return false
}
if Int(partialString) < 0 {
NSBeep()
return false
} else {
return true
}
}
}

Answer 10

// NSTextFieldNumberFormatter+Extension.swift
import Foundation
class TextFieldIntegerValueFormatter: NumberFormatter {
var maxLength: Int
init(maxLength: Int) {
self.maxLength = maxLength
super.init()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
// Ability to reset your field (otherwise you can't delete the content)
// You can check if the field is empty later
if partialString.isEmpty {
return true
}
// Optional: limit input length
if partialString.count > maxLength {
return false
}
// Actual check
return Int(partialString) != nil
}
}
//Need to call like:
myNsTextField.formatter = TextFieldIntegerValueFormatter(maxLength: 6)