Padding string to left

Question

How can one pad a string to left in objective c. E.g if I have an integer value of 6 I want it to be displayed as 06.

I use stringByPaddingToLength: but

Answer 1

Clumsy, but it'll do the job.

@implementation NSString (LeftPadding)

- (NSString *)stringByPaddingTheLeftToLength:(NSUInteger)newLength withString:(NSString *)padString startingAtIndex:(NSUInteger)padIndex
{
    if ([self length] <= newLength)
        return [[@"" stringByPaddingToLength:newLength - [self length] withString:padString startingAtIndex:padIndex] stringByAppendingString:self];
    else
        return [[self copy] autorelease];
}

@end

Then you can do:

NSString *test1 = [@"6" stringByPaddingTheLeftToLength:10 withString:@"0" startingAtIndex:0];
// test1 = "0000000006"

NSString *test2 = [@"asdf" stringByPaddingTheLeftToLength:10 withString:@"qwer" startingAtIndex:0];
// test2 = "qwerqwasdf"

NSString *test3 = [@"More than ten characters" stringByPaddingTheLeftToLength:10 withString:@"bamboo" startingAtIndex:0];
// test3 = "More than ten characters"

NSString *test4 = [test3 stringByPaddingTheLeftToLength:100 withString:test2 startingAtIndex:0];
// test4 = "qwerqwasdfqwerqwasdfqwerqwasdf...qwerqMore than ten characters"