Fragment Cache rely on Fragment.Tag - not compatibile for ex. with ViewPager

[mvvmcross]

Fragment Cache rely on Fragment.Tag - not compatibile for ex. with ViewPager

[thefex]

Mentioned that in other commit.
"a) There is a need to customize "Tag" which is used to identify different fragment instances. Sometimes we do not have control on chosen Fragment tag. ViewPager is an example. (yes we can hack that, cause support viewpager gives "android:switcher" + viewpagerid + ":" + pageindex as tag - but it's just workaround, we gonna fall into this kind of problems over and over again)

Although I have provided overridable method in CachingActivities - GetFragmentTag(Fragment ..) it is useless.
The only way to differentiate same fragment type instances is to use some information provided by viewmodel (like some fragment title/id - information contained in viewmodel).

Problem is: ViewModel is not accesable on PostCreate. ViewModel is set during Fragment.OnViewCreated - too late."

As I've been fixing other issues - I am now sure that we can not use any information from ViewModel - it is not possible to make it works.

I have a pretty good idea in mind:

• lets make Register method in caching activites internal,
• Register method should allow to multiple calls with same parameters passed (let it do nothing in that case)
• if Fragment has MvxOwnedViewModel registration should be done automatically - we just need to find the best moment to do that - perhaps Fragment OnAttach ?

[thefex]

oh and the by the way - registration dictionary must be serialized on instance save, deserialized on activity postcreate

[thefex]

oh that's not closed yet! please reopen the issue, I've just finished bug-fix which provides "auto-register". Gonna merge that tomorrow, when I wake up ;-)