Using non NS_ENUM objective-C enum in swift - swift

Question

I am using the wahoo fitness API and it defines the following objective-C enum:
typedef enum
{
/** No active connection. */
WF_SENSOR_CONNECTION_STATUS_IDLE,
/** The connection is in process of being established. */
WF_SENSOR_CONNECTION_STATUS_CONNECTING,
/** The sensor connection is established and active. */
WF_SENSOR_CONNECTION_STATUS_CONNECTED,
/** The connection was interrupted (usually occurs when fisica is disconnected). */
WF_SENSOR_CONNECTION_STATUS_INTERRUPTED,
/** The connection is in process of being disconnected. */
WF_SENSOR_CONNECTION_STATUS_DISCONNECTING,
} WFSensorConnectionStatus_t;
I can't find a way to use it in swift. I first tried to do a switch/case on it without success. I am at a point I just want to carry on and tried the following:
var connState : WFSensorConnectionStatus_t = WF_SENSOR_CONNECTION_STATUS_IDLE
...
if( connState == WF_SENSOR_CONNECTION_STATUS_IDLE){
But it does not compile:
'WFSensorConnectionStatus_t' is not convertible to 'NSObject'
Any workaround? I read to use WFSensorConnectionStatus_t.WF_SENSOR_CONNECTION_STATUS_IDLE or WF_SENSOR_CONNECTION_STATUS_IDLE.value but it does not work in xcode beta-4.

Answer 1

The workaround to use .value to get the underlying integer doesn't work anymore as of Beta 4, as you said.
Unfortunately an enum is not transferrable to Swift from Objective-C, it needs to be an NS_ENUM.
I have the same setup as you in a project where I need the enum from an Objective-C framework and use it in Swift.
The workaround I did was to create an Objective-C category that contains an NS_ENUM and there I transfer the values from the framework enum to my own NS_ENUM.
Import the category in your bridging header and you should be able to use the enum as you normally would do.
Something like this:
typedef NS_ENUM(NSUInteger, ConnectionStatus) {
ConnectionStatusIdle
}
- (ConnectionStatus)connectionStatus {
if [self getConnectionStatus] == WF_SENSOR_CONNECTION_STATUS_IDLE {
return ConnectionStatusIdle
}
}
Then you should be able to use it like this:
switch myObject.connectionStatus() {
case .Idle:
// do something
break
}

Answer 2

Here is the final complete solution:
WFSensorConnection+SensorConnectionEnumCategory.h
:
#import <Foundation/Foundation.h>
#import <WFConnector/WFConnector.h>
#interface WFSensorConnection (SensorConnectionEnumCategory)
typedef NS_ENUM(NSUInteger, ConnectionStatus) {
ConnectionStatusIdle,
ConnectionStatusConnecting,
ConnectionStatusConnected,
ConnectionStatusInterrupted,
ConnectionStatusDisconnecting
};
- (ConnectionStatus) swift_connectionStatus;
#end
WFSensorConnection+SensorConnectionEnumCategory.m
:
#import "WFSensorConnection+SensorConnectionEnumCategory.h"
#implementation WFSensorConnection (SensorConnectionEnumCategory)
- (ConnectionStatus) swift_connectionStatus{
if ( [self connectionStatus] == WF_SENSOR_CONNECTION_STATUS_IDLE ){
return ConnectionStatusIdle;
} else if ( [self connectionStatus] == WF_SENSOR_CONNECTION_STATUS_CONNECTING ){
return ConnectionStatusConnecting;
} else if ( [self connectionStatus] == WF_SENSOR_CONNECTION_STATUS_CONNECTED ){
return ConnectionStatusConnected;
} else if ( [self connectionStatus] == WF_SENSOR_CONNECTION_STATUS_DISCONNECTING ){
return ConnectionStatusDisconnecting;
} else if ( [self connectionStatus] == WF_SENSOR_CONNECTION_STATUS_INTERRUPTED ){
return ConnectionStatusInterrupted;
}
return 0;
}
#end
Bridging-Header.h
:
#import "WFSensorConnection+SensorConnectionEnumCategory.h"
Usage:
var sensorConnection: WFSensorConnection?
var connState : ConnectionStatus = ConnectionStatus.Idle
connState = sensorConnection!.swift_connectionStatus()
switch connState {
case ConnectionStatus.Idle:
...
}

Answer 3

C-style enums import in Swift like UInt32. So you can do something like:
let state = unsafeBitCast(WF_SENSOR_CONNECTION_STATUS_IDLE, UInt32.self)
if state == unsafeBitCast(WF_SENSOR_CONNECTION_STATUS_IDLE, UInt32.self) {
//do something
}
Upd: In Swift 2.1 (Xcode 7.1 beta 2) all C-style enums conforms Equatable and you can now use it like:
let state = WF_SENSOR_CONNECTION_STATUS_IDLE
if state == WF_SENSOR_CONNECTION_STATUS_IDLE {
//do something
}
Profit :)

Answer 4

Note that there is a CoreFoundation type that is similar to NS_ENUM called CF_ENUM. I've used it on my framework that is mainly C. And yes, Swift does translate it to a Swift enum.
There is also something similar for NS_OPTIONS called CF_OPTIONS.