NSLog in Objective-C is function call that is useful during debugging of a program. A typical NSLog example is
NSLog(@” How to use NSLog”);
The above statement prints the message ” How to use NSLog ” in console window. If you want to print the value of Objective-C variable or data type then you need to pass the relevant formatting parameter depending on data type. We have already seen different datatype and qualifiers in Objective-C, below is example Objective-C program with NSLog formatting option for each datatypes.
#import <Foundation/Foundation.h>
int main(int argc, const char * argv[])
{
int i = 5;
float f = 5.3;
double d = 66.76;
long int li = 22;
short int si = 12;
char c = ‘W’;
signed int sint = 34;
unsigned int uint = –23;
int o = 024;
int h = 0xAD;
long long ll = 45;
long double lf = 34.5;
unsigned long long ull = 12;
NSString *msg = @”NSLog Message”;
@autoreleasepool {
NSLog(@” print int %d”, i);
NSLog(@” print float %f”, f); // use %e for exponential
NSLog(@” print double %f”, d); // use %e for exponential
NSLog(@” print long int %li”, li);
NSLog(@” print short int %i”, si);
NSLog(@” print char %c”, c);
NSLog(@” print signed int %i”, sint);
NSLog(@” print unsigned int %u”, uint);
NSLog(@” print octal %o”, o);
NSLog(@” print hexadecimal %X”, h);
NSLog(@” print long long %lld”, ll);
NSLog(@” print long double %Lf”, lf);
NSLog(@” print unsigned long long %llu”, ull);
NSLog(@” print Object %@”, msg);
}
return 0;
}
The console output of the above Objective-C program is shown below
2013-03-04 07:25:10.187 NSLog Example[362:303] print int 5
2013-03-04 07:25:10.189 NSLog Example[362:303] print float 5.300000
2013-03-04 07:25:10.189 NSLog Example[362:303] print double 66.760000
2013-03-04 07:25:10.190 NSLog Example[362:303] print long int 22
2013-03-04 07:25:10.190 NSLog Example[362:303] print short int 12
2013-03-04 07:25:10.190 NSLog Example[362:303] print char W
2013-03-04 07:25:10.191 NSLog Example[362:303] print signed int 34
2013-03-04 07:25:10.191 NSLog Example[362:303] print unsigned int 4294967273
2013-03-04 07:25:10.192 NSLog Example[362:303] print octal 24
2013-03-04 07:25:10.192 NSLog Example[362:303] print hexadecimal AD
2013-03-04 07:25:10.193 NSLog Example[362:303] print long long 45
2013-03-04 07:25:10.193 NSLog Example[362:303] print long double 34.500000
2013-03-04 07:25:10.194 NSLog Example[362:303] print unsigned long long 12
2013-03-04 07:25:10.194 NSLog Example[362:303] print Object NSLog Message
int %d or %i
float %f or %e
double %f or %e
long int %li
short int %i
char %c
signed int %i
unsigned int %u
octal %o
hexa %X
long long %lld
long double %Lf
unsigned long long %llu
object %@
