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iosnsstringnscharacterset

NSString method stringByTrimmingCharactersInSet: not trimming comma

I have the following code for removing extra characters from some strings representing numbers:

NSCharacterSet *charactersToKeep = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
NSCharacterSet *charactersToBeRemoved = [charactersToKeep invertedSet];

NSString *myString = [dictionary objectForKey:@"MyKey"];
myString = [myString stringByTrimmingCharactersInSet:charactersToBeRemoved];
myString = [myString stringByReplacingOccurrencesOfString:@"," withString:@""];

After the method stringByTrimmingCharactersInSet:, all the extra characters but the comma are removed. After the call to stringByReplacingOccurencesOfString: the comma is removed. Why isn't it removed after the first call?

Here is a sample of what myString looks like after each line of code:

myString = " $9,959 "
myString = "9,959"
myString = "9959"

I also tried 

NSCharacterSet *charactersToBeRemoved = [NSCharacterSet decimalDigitCharacterSet];

and got the same result.

Solution

  • stringByTrimmingCharactersInSet: only trims characters from the ends of the string, not on the inside.