iFrame vs XFBML

I'm getting a bit confused by these two operations. Before I wrote this question, I looked at 5 or 6 other articles concerning the two but, I still couldn't get a clear solution to what I need to know.

Am I correct in saying that the use of 'iFrame' in codes is NOT compatible with a LOT of mobile devices? I've always seen XFBML is more appropriate. I even tried it开发者_StackOverflow中文版 on some of my mobile devices and had some "mixed" results. Can someone please set me on the 'right' course of code?

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use xFBML only when you are sure that you need a particular function provided by xFBML, e.g. multi-friend-selector.

Otherwise, iframe is always the choice now.