在swift中使用非NS_ENUM objective-C枚举

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 .