dynamic string format with NSString stringWithFormat

Question

I\'ve been trying to make a dynamic string format so that through user options precision or padding could be somewhat user defined.

An example includes, the padding of

Answer 1

There's a better way to do this.

... stringWithFormat:@"Hour: %0*i", length, hour]; // note the asterisk

where length is the number of digits you want. Use 1 to get no leading zeros, use 2 to get a length of 2 with leading zeros as needed.

FYI - to solve what you originally tried you need to do it in two steps:

NSString *dynFmt = [NSString stringWithFormat:@"Hour: %%%@i", padding];
NSString *res = [NSString stringWithFormat:dynFmt, hour];