how to validate textfield that allows only single decimal point in textfield? - iphone

Question

I need to restrict user to enter only two digit after decimal point. I have achieved this by following code in textfield delegate shouldChangeCharactersInRange. But its allowing to enter more than one dot. how to restrict this? Thanks in advance.
NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
NSArray *sep = [newString componentsSeparatedByString:#"."];
if([sep count]>=2)
{
NSString *sepStr=[NSString stringWithFormat:#"%#",[sep objectAtIndex:1]];
NSLog(#"sepStr:%#",sepStr);
return !([sepStr length]>2);
}
return YES;

Answer 1

The best way is to use Regular Expression in shouldChangeCharactersInRange: delegate method like this
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
NSString *newStr = [textField.text stringByReplacingCharactersInRange:range withString:string];
NSString *expression = #"^([0-9]*)(\\.([0-9]+)?)?$";
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression
options:NSRegularExpressionCaseInsensitive
error:nil];
NSUInteger noOfMatches = [regex numberOfMatchesInString:newStr
options:0
range:NSMakeRange(0, [newStr length])];
if (noOfMatches==0){
return NO;
}
return YES;
}
After implementing this valid strings are:
12.004546
4546.5456465
.5464
0.454
So on....
You can also restrict number of integer after decimal by using this Regular Expression#"^([0-9]*)(\\.([0-9]{0,2})?)?$"
After implementing this valid strings are:
12.00
4546.54
.54
0.45

Answer 2

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
NSString *sepStr;
NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
NSArray *sep = [newString componentsSeparatedByString:#"."];
if([sep count]>=2)
{
sepStr=[NSString stringWithFormat:#"%#",[sep objectAtIndex:1]];
NSLog(#"sepStr:%#",sepStr);
if([sepStr length] >2)
{
return NO;
}
else
{
return YES;
}
}
return YES;
}

Answer 3

When a dot is entered, you should check whether a dot is present already, and return NO if it is present.
NSString * newString = [textField.text stringByReplacingCharactersInRange: range withString: string];
NSArray * sep = [newString componentsSeparatedByString: #"."];
if([string isEqualToString:#"."] && [sep count] > 1){
//already a . is there.. so don't allow new one
return NO;
}
if ([sep count] >= 2) {
NSString * sepStr = [NSString stringWithFormat: #"%#", [sep objectAtIndex: 1]];
NSLog(#"sepStr:%#", sepStr);
return !([sepStr length] > 2);
}
return YES;

Answer 4

Updated answer for Swift 3 using the reg ex "^([0-9]*)(\\.([0-9]+)?)?$":
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let newText = ((textField.text ?? "") as NSString).replacingCharacters(in: range, with: string)
let expression = "^([0-9]*)(\\.([0-9]+)?)?$"
guard let regex = try? NSRegularExpression(pattern: expression, options: .caseInsensitive) else {
return false
}
let noOfMatches = regex.numberOfMatches(in: newText, options: [], range: NSMakeRange(0, newText.characters.count))
return noOfMatches > 0
}

Answer 5

You can use this method:
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSRange temprange = [textField.text rangeOfString:#"."];
if ((temprange.location != NSNotFound) && [string isEqualToString:#"."])
{
return NO;
}
return YES;
}

Answer 6

NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
NSArray *sep = [newString componentsSeparatedByString:#"."];
if([string isEqualToString:#"."]){
if([textField.text containsString:#"."]){
return NO;
}
}
if([sep count] >= 2)
{
NSString *sepStr=[NSString stringWithFormat:#"%#",[sep objectAtIndex:1]];
return !([sepStr length]>2);
}
return YES;
}