UIDeviceHardware.h

//
//  UIDeviceHardware.h
//
//  Used to determine EXACT version of device software is running on.

#import <Foundation/Foundation.h>

@interface UIDeviceHardware : NSObject 
+ (NSString *) platform;
+ (NSString *) platformString;
@end

UIDeviceHardware.m

//
//  UIDeviceHardware.m
//
//  Used to determine EXACT version of device software is running on.

#import "UIDeviceHardware.h"
#include <sys/types.h>
#include <sys/sysctl.h>

@implementation UIDeviceHardware

+ (NSString *) platform{
    size_t size;
    sysctlbyname("hw.machine", NULL, &size, NULL, 0);
    char *machine = malloc(size);
    sysctlbyname("hw.machine", machine, &size, NULL, 0);
    NSString *platform = [NSString stringWithUTF8String:machine];
    free(machine);
    return platform;
}

+ (NSString *) platformString{
    // @see http://theiphonewiki.com/wiki/Models
    NSString *platform = [self platform];
    
    // iPhone
    if ([platform isEqualToString:@"iPhone1,1"])    return @"iPhone 1G";
    if ([platform isEqualToString:@"iPhone1,2"])    return @"iPhone 3G";
    if ([platform isEqualToString:@"iPhone2,1"])    return @"iPhone 3GS";
    if ([platform isEqualToString:@"iPhone3,1"])    return @"iPhone 4 (GSM)";
    if ([platform isEqualToString:@"iPhone3,2"])    return @"iPhone 4 (GSM Rev A)";
    if ([platform isEqualToString:@"iPhone3,3"])    return @"iPhone 4 (CDMA)";
    if ([platform isEqualToString:@"iPhone4,1"])    return @"iPhone 4S";
    if ([platform isEqualToString:@"iPhone5,1"])    return @"iPhone 5 (GSM)";
    if ([platform isEqualToString:@"iPhone5,2"])    return @"iPhone 5 (CDMA)";
    if ([platform isEqualToString:@"iPhone5,3"])    return @"iPhone 5c (GSM)";
    if ([platform isEqualToString:@"iPhone5,4"])    return @"iPhone 5c (Global)";
    if ([platform isEqualToString:@"iPhone6,1"])    return @"iPhone 5s (GSM+CDMA)";
    if ([platform isEqualToString:@"iPhone6,2"])    return @"iPhone 5s (Global)";
    
    // iPod
    if ([platform isEqualToString:@"iPod1,1"])      return @"iPod Touch 1G";
    if ([platform isEqualToString:@"iPod2,1"])      return @"iPod Touch 2G";
    if ([platform isEqualToString:@"iPod3,1"])      return @"iPod Touch 3G";
    if ([platform isEqualToString:@"iPod4,1"])      return @"iPod Touch 4G";
    if ([platform isEqualToString:@"iPod5,1"])      return @"iPod Touch 5G";

    // iPad
    if ([platform isEqualToString:@"iPad1,1"])      return @"iPad";
    if ([platform isEqualToString:@"iPad2,1"])      return @"iPad 2 (WiFi)";
    if ([platform isEqualToString:@"iPad2,2"])      return @"iPad 2 (GSM)";
    if ([platform isEqualToString:@"iPad2,3"])      return @"iPad 2 (CDMA)";
    if ([platform isEqualToString:@"iPad2,4"])      return @"iPad 2 (WiFi Rev A)";
    if ([platform isEqualToString:@"iPad3,1"])      return @"iPad 3 (WiFi)";
    if ([platform isEqualToString:@"iPad3,2"])      return @"iPad 3 (GSM+CDMA)";
    if ([platform isEqualToString:@"iPad3,3"])      return @"iPad 3 (GSM)";
    if ([platform isEqualToString:@"iPad3,4"])      return @"iPad 4 (WiFi)";
    if ([platform isEqualToString:@"iPad3,5"])      return @"iPad 4 (GSM)";
    if ([platform isEqualToString:@"iPad3,6"])      return @"iPad 4 (GSM+CDMA)";
    if ([platform isEqualToString:@"iPad4,1"])      return @"iPad Air (WiFi)";
    if ([platform isEqualToString:@"iPad4,2"])      return @"iPad Air (Cellular)";

    // iPad Mini
    if ([platform isEqualToString:@"iPad2,5"])      return @"iPad Mini (WiFi)";
    if ([platform isEqualToString:@"iPad2,6"])      return @"iPad Mini (GSM)";
    if ([platform isEqualToString:@"iPad2,7"])      return @"iPad Mini (GSM+CDMA)";
    if ([platform isEqualToString:@"iPad4,4"])      return @"iPad Mini Retina (WiFi)";
    if ([platform isEqualToString:@"iPad4,5"])      return @"iPad Mini Retina (Cellular)";

    // Xcode iOS Simulator
    if ([platform isEqualToString:@"i386"])         return @"iOS i386 Simulator";
    if ([platform isEqualToString:@"x86_64"])       return @"iOS x86_64 Simulator";
    return platform;
}

@end

usage.txt

Usage:
NSLog(@"platformString %@", [UIDeviceHardware platformString]);