Integer literal overflows when stored into 'Int'

UInt32(0x8BC34AFF) creates a UInt32 by calling an initializer. The UInt32 initializer you are calling is:

init(_ v: Int)

The problem is that on a 32-bit device (iPhone5 and earlier), type Int is 32-bits. So, the constant you are passing 0x8BC34AFF overflows the Int that you are passing to the initializer of UInt32.

The way to have this work on both 32-bit and 64-bit devices is to cast the integer literal to the type:

let primary = 0x8BC34AFF as UInt32

Alternatively, declare the variable to be UInt32 and just assign the constant:

let primary:UInt32 = 0x8BC34AFF

You may also run into this issue if you have not selected any device or simulator before trying to run unit tests. (in that case default Generic iOS Device is selected). I have received this error for some integer values in unit test classes.