Helper functions for applying code between different iOS versions at runtime.

DeviceHelper.h

//
//  DeviceHelper.h
//
//  Created by Daniel Thorpe on 25/06/2012.
//  Copyright (c) 2012 Blinding Skies Limited. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface DeviceHelper : NSObject

+ (void)iOS4OrNewer:(void(^)(void))shiny older:(void(^)(void))old;
+ (void)iOS5OrNewer:(void(^)(void))shiny older:(void(^)(void))old;
+ (void)iOS6OrNewer:(void(^)(void))shiny older:(void(^)(void))old;

@end

DeviceHelper.m

//
//  DeviceHelper.m
//
//  Created by Daniel Thorpe on 25/06/2012.
//  Copyright (c) 2012 Blinding Skies Limited. All rights reserved.
//

#import "DeviceHelper.h"

typedef NS_ENUM(NSUInteger, iOSMajorVersions) {
    iOSMajorVersion4 = 4,
    iOSMajorVersion5 = 5,
    iOSMajorVersion6 = 6
};

@implementation DeviceHelper

+ (void)iOS4OrNewer:(void(^)(void))shiny older:(void(^)(void))old {
    [DeviceHelper major:iOSMajorVersion4 orNewer:shiny older:old];
}

+ (void)iOS5OrNewer:(void(^)(void))shiny older:(void(^)(void))old {
    [DeviceHelper major:iOSMajorVersion5 orNewer:shiny older:old];
}

+ (void)iOS6OrNewer:(void(^)(void))shiny older:(void(^)(void))old {
    [DeviceHelper major:iOSMajorVersion6 orNewer:shiny older:old];
}

+ (void)major:(iOSMajorVersions)threshold orNewer:(void(^)(void))shiny older:(void(^)(void))old {
    // Get the major system OS version
    NSInteger major = [[[[UIDevice currentDevice] systemVersion] substringToIndex:1] integerValue];
    
    if (major >= threshold) {
        if (shiny) shiny();
    } else {
        if (old) old();
    }
}

@end