Reference the LaunchImage from Asset Catalog

gistfile1.m

NSDictionary *dict = @{@"320x480" : @"LaunchImage-700", @"320x568" : @"LaunchImage-700-568h", @"375x667" : @"LaunchImage-800-667h", @"414x736" : @"LaunchImage-800-Portrait-736h"};
NSString *key = [NSString stringWithFormat:@"%dx%d", (int)[UIScreen mainScreen].bounds.size.width, (int)[UIScreen mainScreen].bounds.size.height];
UIImage *launchImage = [UIImage imageNamed:dict[key]];