objective c - Specify floating point number accuracy in NSString -

i'm trying specify accuracy of floating pointer number in nsstring keep on getting error:

format specifies type 'double' argument has type 'nsstring *'

here code:

nsstring *tmplabel = [tmp description]; temp.text = [nsstring  stringwithformat: @"%.fº", tmplabel]; 

what doing wrong?

your tmplabel nsstring, should double.

if sure tmplabel holds number can parsed simple double, can use doublevalue on it. otherwise might have more elaborate conversion error handling etc.

here's down-to-earth simple way it:

temp.text = [nsstring  stringwithformat: @"%.fº", [tmplabel doublevalue]]; 

the doublevalue method (and close relatives integervalue, , similar) interprets string's content , if beginning of string can read number, convert , return appropriate primitive type. in case primitive type double.

you can not make type cast object (anything ns*) primitive type, have go through sort of interpretation or programmatic conversion.

last, please notice using doublevalue directly on user input shortcut want re-visit @ point, make mental note of re-implementing using either number formatter or nsscanner later. idea why, try enter non-numerical data , see if happy result.

finally, set accuracy (i.e., number of decimals after decimal point) asked for, see either prince's answer below, or dharaparekh's.