CFDictionary在Swift3中获取键的值 [英] CFDictionary get Value for Key in Swift3

问题描述

我在访问CFDictionary中的特定(或任何)键时遇到问题. 老实说，我并没有真正掌握在Swift中执行此操作的方式，而且我认为它过于复杂...

I've a problem with accessing a specific (or any) key in a CFDictionary. Honestly I don't really get the way you need to do this in Swift and I think it's overly complicated...

我的代码:

if let session = DASessionCreate(kCFAllocatorDefault) {
let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: [], options: [])!
for volume in mountedVolumes {
    if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL) {
        let diskinfo = DADiskCopyDescription(disk);   

        var volumeValue = CFDictionaryGetValue(diskinfo, <#T##key: UnsafeRawPointer!##UnsafeRawPointer!#>)


    }
}

我要实现的目标:将键或字段 DAVolumeNetwork 的值放入变量 volumeValue 中. 我想我需要将 kDADiskDescriptionVolumeNetworkKey 传递给 CFDictionaryGetValue 方法吗?我该如何实现?

What I want to achieve: Get the Value for the Key or field DAVolumeNetwork into the variable volumeValue. I guess I need to pass the kDADiskDescriptionVolumeNetworkKey to the CFDictionaryGetValue Method? How do I achieve this?

推荐答案

在Swift中不要使用CFDictionary. (有可能，但不值得付出努力，请参阅下文.)

Don't use CFDictionary in Swift. (It is possible, but not worth the effort, see below.)

• CFDictionary是免费电话 与NSDictionary桥接，又可以转换为Swift Dictionary.
• kDADiskDescriptionVolumeNetworkKey键的值是一个 CFBoolean可以转换为Swift Bool.

• CFDictionary is toll-free bridged with NSDictionary, which in turn can be cast to a Swift Dictionary.
• The value of the kDADiskDescriptionVolumeNetworkKey key is a CFBoolean which can be cast to a Swift Bool.

示例:

if let session = DASessionCreate(kCFAllocatorDefault),
    let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: []) {
    for volume in mountedVolumes {
        if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL),
            let diskinfo = DADiskCopyDescription(disk) as? [NSString: Any] {

            if let networkValue = diskinfo[kDADiskDescriptionVolumeNetworkKey] as? Bool {
                print(networkValue)
            }
        }
    }
}

---

仅出于完整性考虑:这是必要的指针 忙于在Swift 3中调用CFDictionaryGetValue

---

Just for the sake of completeness: This is the necessary pointer juggling to call CFDictionaryGetValue in Swift 3:

if let session = DASessionCreate(kCFAllocatorDefault),
    let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: []) {
    for volume in mountedVolumes {
        if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL),
            let diskinfo = DADiskCopyDescription(disk) {

            if let ptr = CFDictionaryGetValue(diskinfo, Unmanaged.passUnretained(kDADiskDescriptionVolumeNetworkKey).toOpaque()) {
                let networkValue = Unmanaged<NSNumber>.fromOpaque(ptr).takeUnretainedValue()
                print(networkValue.boolValue)
            }
        }
    }
}

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