//Place this in the .m file outside any function.

BOOL isiPhone(){
    return (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone);
}
BOOL isiPad(){
    return (UI_USER_INTERFACE_IDIOM() != UIUserInterfaceIdiomPhone);
}


//Then call it from any function like this:
if (isiPhone()) {
	//This device is an iphone
}

if (isiPad()) { 
	//This device is an iPad
}

Easy way for Checking Device Type

Objective C