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12. Objects > Message anatomy
A message send is always surrounded by square brackets, and it always has at least two parts:
a pointer to the object that is receiving the message
the name of the method to be triggered
A message send (like a function call) can also have arguments. Let’s look at an example.
NSDate objects represent a particular date and time. An instance of NSDate can tell you the difference (in seconds) between the date/time it represents and 12:00AM (GMT) on Jan 1, 1970. Ask yours this question by sending the message timeIntervalSince1970 to the NSDate object pointed to by now.
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[])
{
@autoreleasepool {
NSDate *now = [NSDate date];
NSLog(@"The date is %@", now);
double seconds = [now timeIntervalSince1970];
NSLog(@"It has been %f seconds since the start of 1970.", seconds);
}
return 0;
}
