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

Question

An existing objective-C method has the following signature:
-(BOOL)barcodeSetScanBeep:(BOOL)enabled volume:(int)volume beepData:(int *)data length:(int)length error:(NSError **)error;
Note that beepData: expects (int *).
This method can be used from objective-C by passing in a C array:
int beepData[] = {1200,100};
How can I call the same method from Swift? My best attempt, let beepData: [Int] = [1200, 100], doesn't compile.

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.