#ifdef replacement in the Swift language

Question

In C/C++/Objective C you can define a macro using compiler preprocessors. Moreover, you can include/exclude some parts of code using compiler preprocessors.

Answer 1

This builds on Jon Willis's answer that relies upon assert, which only gets executed in Debug compilations:

func Log(_ str: String) { 
    assert(DebugLog(str)) 
}
func DebugLog(_ str: String) -> Bool { 
    print(str) 
    return true
}

My use case is for logging print statements. Here is a benchmark for Release version on iPhone X:

let iterations = 100_000_000
let time1 = CFAbsoluteTimeGetCurrent()
for i in 0 ..< iterations {
    Log ("⧉ unarchiveArray:\(fileName) memoryTime:\(memoryTime) count:\(array.count)")
}
var time2 = CFAbsoluteTimeGetCurrent()
print ("Log: \(time2-time1)" )

prints:

Log: 0.0

Looks like Swift 4 completely eliminates the function call.