Get the main storyboard in an iOS app as set by the .plist file. (You may need to change the return type to id if you are on 6.1 or earlier.)

UIStoryboard+LDMain.h

#import <UIKit/UIKit.h>

@interface UIStoryboard (LDMain)

+ (instancetype)mainStoryboard;

@end

UIStoryboard+LDMain.m

#import "UIStoryboard+LDMain.h"

UIStoryboard *_mainStoryboard = nil;

@implementation UIStoryboard (LDMain)

+ (instancetype)mainStoryboard {
    if (!_mainStoryboard) {
        NSBundle *bundle = [NSBundle mainBundle];
        NSString *storyboardName = [bundle objectForInfoDictionaryKey:@"UIMainStoryboardFile"];
        _mainStoryboard = [UIStoryboard storyboardWithName:storyboardName bundle:bundle];
    }
    return _mainStoryboard;
}

@end