How to detect a cracked iPhone App and a jailbroken device (different methods)

Question

I\'m building a blacklisting service for cracked iPhone apps and I am curious if I missed a method for detecting cracked apps.

In the moment following app crack detectio

Answer 1

NEVER try and block jailbroken devices from using your app, just cracked ones. If you block jailbroken devices they'll be forced to use a patched version with all the checks removed.
Also ALL my devices are jailbroken so if a developer blocks jailbroken devices I would have to ignore their apps. Over 10% of all iDevices are jailbroken so this is a very bad idea.

EDIT: As I'm getting lots of down votes for this I'll post some methods to detect a jailbreak.

- (BOOL)fileExistsAtPath:(NSString *)path{
    NSLog(@"Check if file '%@' exists", path);

    struct stat buffer;   
    return stat([path UTF8String], &buffer) == 0;
}

- (BOOL)jailbroken{
    return ([self fileExistsAtPath:@"/Applications/Cydia.app"]);
}