Command Line Arguments in Objective-C

Command Line Arguments in Detail

In Objective-C, command-line arguments are text strings passed to a program when it runs from the command line. They provide input parameters or options that control the program’s behavior or supply data for processing.

The main function of an Objective-C program receives two parameters: argc and argv.

• argc (short for “argument count”) is an integer representing the number of arguments passed to the program.
• argv (short for “argument vector”) is an array of char pointers, each pointing to a command-line argument.

./example -debug config.json output.log

In this case:

1. argc will be 4, as there are four arguments.
2. argv will hold the following values:

• argv[0] = “./example”
• argv[1] = “-debug”
• argv[2] = “config.json”
• argv[3] = “output.log”

Example 1:

// Objective-C program to demonstrate command-line arguments
#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    for (int i = 0; i < argc; i++)
    {
        NSString *arg = [NSString stringWithUTF8String:argv[i]];
        NSLog(@"Argument %d: %@", i, arg);
    }
    [pool drain];
    return 0;
}

Output:

./example -debug config.json output.log

The output will be:

Argument 0: ./example
Argument 1: -debug
Argument 2: config.json
Argument 3: output.log