Objective-C. Sample with comments

Here is a simple Objective-C program where almost all lines have comments:

// the following directive import is the same as include but it ensures
// that the file is included only once.
//
// The following line includes the headers for all the classes in 
// the Foundation framework. The headers are precompiled, so this
// approach is not as computationally intensive as it sounds.
#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) 
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // Variable array is declared here. It is a pointer to an instance 
    // of NSMutableArray. Note that no array exists yet.
    NSMutableArray *array;
    
    //Here the array is created.
    array = [[NSMutableArray alloc] init];
    int i;
    for (i = 0; i < 10; i++)
    {
        NSNumber *newNumber = [[NSNumber alloc] initWithInt:(i * 3)];
        
        // The array does not make copies of the NSNumber objects.
        // Instead it simply keeps a list of pointers to the
        // NSNumber objects.
        [array addObject:newNumber];
    }
    
    for (i = 0; i < 10; i++)
    {
        NSNumber *numberToPrint = [array objectAtIndex:i];
        // %@ - the object gets send the message description,
        // and the string it returns replaces %@ in the string.
        NSLog(@"The number at index %d is %@", i, numberToPrint);
    }
    
    [pool drain];
    return 0;
}