Помог следующий совет:

- If “Valid Architectures” is set only to armv6 and armv7, delete both. Restart Xcode. I do not know why but some of you reported that it helped. Set “Valid Architectures” to $(ARCHS_STANDARD_32_BIT). Valid Architectures will show armv6 and armv7 again but this time it may compile just fine. Strange though.