space age.m

//
//  main.m
//  Space Age
//
//  Created by Michael Redig on 10/9/19.
//  Copyright © 2019 Red_Egg Productions. All rights reserved.
//

#import <Foundation/Foundation.h>

double mercuryAge(double seconds) {
	return (seconds / 31557600) / 0.2408467;
}

double venusAge(double seconds) {
	return (seconds / 31557600) / 0.61519726;
}

double earthAge(double seconds) {
	return seconds / 31557600;
}

double marsAge(double seconds) {
	return (seconds / 31557600) / 1.8808158;
}

double jupiterAge(double seconds) {
	return (seconds / 31557600) / 11.862615;
}

double saturnAge(double seconds) {
	return (seconds / 31557600) / 29.447498;
}

double uranusAge(double seconds) {
	return (seconds / 31557600) / 84.016846;
}

double neptuneAge(double seconds) {
	return (seconds / 31557600) / 164.79132;
}

NSString* spaceAger(double seconds) {
	NSString* mercury = [NSString stringWithFormat:@"%.02f Mercury years", mercuryAge(seconds)];
	NSString* venus = [NSString stringWithFormat:@"%.02f Venus years", venusAge(seconds)];
	NSString* earth = [NSString stringWithFormat:@"%.02f Earth years", earthAge(seconds)];
	NSString* mars = [NSString stringWithFormat:@"%.02f Mars years", marsAge(seconds)];
	NSString* jupiter = [NSString stringWithFormat:@"%.03f Jupiter years", jupiterAge(seconds)];
	NSString* saturn = [NSString stringWithFormat:@"%.04f Saturn years", saturnAge(seconds)];
	NSString* uranus = [NSString stringWithFormat:@"%.04f Uranus years", uranusAge(seconds)];
	NSString* neptune = [NSString stringWithFormat:@"%.04f Neptune years", neptuneAge(seconds)];

	return [NSString stringWithFormat:@"With %.0f seconds, you would be %@, %@, %@, %@, %@, %@, %@, and %@ old.", seconds, mercury, venus, earth, mars, jupiter, saturn, uranus, neptune];
}

int main(int argc, const char * argv[]) {
	@autoreleasepool {
		NSString* spaceAge = spaceAger(31557600 * (31 + (9.0 / 365.0)));
		NSLog(@"%@", spaceAge);
	}
	return 0;
}

For clarity I would use a variable for the 31557600 value that's used numerous times. That's a magic number and prone to error if it's a literal number (not a constant).

Always write NSString *mercury

Use more constants for 31, 9, 365

using a constants is a great idea.

not sure what you mean with mercury?