iOS 应用版本号比较

NSDictionary *infoDict = [[NSBundle mainBundle] infoDictionary];
    NSString *vison = infoDict[@"CFBundleVersion"];
    //    NSString *vison = @"1.2.5";
    NSString *vison2 = @"1.13.4";    
    if ([vison compare:vison2 options:NSNumericSearch] == NSOrderedDescending)
    {
        NSLog(@"%@ is bigger",vison);
    } else {
        NSLog(@"%@ is bigger",vison2);  
    }