NSString stringWithFormat adding a percent [duplicate]
%
being the character beginning printf-style formats, it simply needs to be doubled:
float someFloat = 40.233f;NSString *str = [NSString stringWithFormat:@"%.02f%%",someFloat];
The escape code for a percent sign is “%%”, so your code would look like this
[NSString stringWithFormat:@"%d%%", someDigit];
This is also true for NSLog() and printf() formats.
Cited from How to add percent sign to NSString.