You would have already seen using NSLog in the hello world example. A simple example is shown below.

int main(int argc, const char * argv[])
    //  Autoreleasepool used in main for automatic memory management.
    @autoreleasepool {
		int a = 5;
		NSLog(@"Log value is %d",a);        
    return 0;

You can see in the above example how to use NSLog. You need to use the type formatters like %d, %f, %s, %@ for integer, float, string and objects respectively.