Adam is on the right track, but not quite there. You do want to use +stringWithFormat:, but not quite as he suggested. If you want to pad "someString" to (say) a minimum of 12 characters, you'd use a width specifier as part of the format. Since you want the result to be left-justified, you need to precede the width specifier with a minus:
NSString *padded = [NSString stringWithFormat:@"%-12@", someString];
Or, if you wanted the result to be exactly 12 characters, you can use both minimum and maximum width specifiers:
NSString *padded = [NSString stringWithFormat:@"%-12.12@", someString];
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