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If doing this, $(ARCHS_STANDARD_32_BIT), like answers here suggested, Arm64 architecture in xcode 5.1

Will these 32 bit app be compatible with 64 bit and run well on iPhone 5S or even later?

Community
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S1U
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  • yes, but not vise versa – Basheer_CAD May 04 '14 at 15:21
  • Have you a reason _not_ to be 64-bit compatible? – matt May 04 '14 at 15:36
  • @matt cause I found something wrong always at `search library paths` even I empty this and reimport 3rd framework like Admob and Wechat back and forth. I'm tired of this so changed `$(ARCHS_STANDARD)`, and back to 32-bit. – S1U May 04 '14 at 15:47
  • Yes, that's a pretty good reason (dependency on 3rd party framework that isn't updated to 64-bit yet). So you really have no choice at this point. – matt May 04 '14 at 16:29

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Yes they will run on an iPhone 5S. The iPhone 5S will load the 32-bit framework into shared memory on the device, and run the app using that.

But it is worth while supporting both 32-bit and 64-bit architectures to reduce the memory usage your app consumes on a 64-bit device - even if you're not using any 64-bit specific features.

Tim
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  • You mean the same one 32-bit app will cost more memories on 64-bit vs. on 32-bit, is my understanding right? – S1U May 04 '14 at 15:32
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    Yes, in the sense that you are requiring a second copy of the system to load. Please watch "Architecting Modern iOS Games" video from the current set of Apple Tech Talks. It explains this very well (and says nothing about games...) – matt May 04 '14 at 15:34
  • @iOS.dev Yes, if you run a 32-bit app, on a 64-bit device, the device will need to load the 32-bit frameworks into shared memory. Whereas if it supports 64-bit as well as 32-bit, the 64-bit device will be able to just use the already loaded 64-bit frameworks in shared memory. – Tim May 04 '14 at 15:41