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swiftloggingswift2nslog

How to invoke method with CVaListPointer parameters in Swift

How should I invoke the following method? The method belongs to a class that prints logs.

func log(format: String!, withParameters valist: CVaListPointer)

What I want to achieve, would look like this in Objective-C:

NSLog(@"Message %@ - %@", param1, param2);

Any ideas?

Solution

  • CVaListPointer is the Swift equivalent of the C va_list type and can be created from an [CVarArgType] array using withVaList().

    Example:

    func log(format: String!, withParameters valist: CVaListPointer) {
    NSLogv(format, valist)
}

let args: [CVarArgType] = [ "foo", 12, 34.56 ] 
withVaList(args) { log("%@ %ld %f", withParameters: $0) }

    Output:

    2016-04-27 21:02:54.364 prog[6125:2476685] foo 12 34.560000

    For Swift 3, replace CVarArgType by CVarArg.