How can I use Swift to call an objective-C method that expects an argument of type (int *)?

Question

An existing objective-C method has the following signature:

-(BOOL)barcodeSetScanBeep:(BOOL)enabled volume:(int)volume beepData:(int *)data length:(int)length er         


        

Answer 1

int is a C 32-bit integer and mapped to Swift as Int32.

A int * parameter is mapped to Swift as UnsafeMutablePointer<Int32>, and you can pass a variable array as "inout parameter" with &.

So it should roughly look like this:

var beepData : [ Int32 ] = [ 1200, 100 ]
var error : NSError?
if !DTDevices.sharedDevice().barcodeSetScanBeep(true, volume: Int32(100),
                beepData: &beepData, length: Int32(beepData.count),
                error: &error) {
    println(error!)
}

Swift defines also a type alias

/// The C 'int' type.
typealias CInt = Int32

so you could replace Int32 by CInt in above code if you want to emphasize that you are working with C integers.

For more information, see "Interacting with C APIs" in the "Using Swift with Cocoa and Objective-C" documentation.