我正在关注苹果的记录示例 https://developer.apple.com/documentation/foundation/urlresourcekey/checking_volume_storage_capacity了解如何查询我的设备上的可用磁盘空间。
我在我的中使用下面的代码applicationDidFinishLaunchingWithOptions
:
let fileURL = URL(fileURLWithPath:"/")
do {
let values = try fileURL.resourceValues(forKeys: [
.volumeAvailableCapacityKey,
.volumeAvailableCapacityForImportantUsageKey,
.volumeAvailableCapacityForOpportunisticUsageKey,
.volumeTotalCapacityKey
])
print("Available Capacity: \(Float(values.volumeAvailableCapacity!)/1000000000)GB")
print("ImportantUsage Capacity: \(Float(values.volumeAvailableCapacityForImportantUsage!)/1000000000)GB")
print("Opportunistic Capacity: \(Float(values.volumeAvailableCapacityForOpportunisticUsage!)/1000000000)GB")
print("Total Capacity: \(Float(values.volumeTotalCapacity!)/1000000000)GB")
} catch {
print("Error retrieving capacity: \(error.localizedDescription)")
}
这会记录以下内容:
Available Capacity: 3.665879GB
ImportantUsage Capacity: 0.0GB
Opportunistic Capacity: 0.0GB
Total Capacity: 63.989494GB
Why are volumeAvailableCapacityForImportantUsage
and volumeAvailableCapacityForOpportunisticUsage
为零,什么情况下会发生这种情况?
背景:
- 我通过 xCode 10.2.1 在我自己的 64GB iPhone SE 上运行此实验(因此总容量看起来是正确的)
- 我的 iPhone 运行的是 iOS 11
- iTunes 声称我的设备有 10.27GB“免费”空间
- 我正在尝试解决这个问题,以便我知道我的用户是否有足够的空间来下载大型(40MB+)应用内购买
注意:这是not与这个问题 https://stackoverflow.com/questions/26198073/query-available-ios-disk-space-with-swift/47463829。我知道如何查询可用空间。我想了解该查询的结果。
问题是您正在尝试获取 / 处的系统卷的容量,该系统卷是文件系统的根目录。这个 API 的行为很奇怪,但你可以获得你需要的信息。如果您使用应用程序的文档目录,则FileManager
方法和.volumeAvailableCapacityKey
仍然会产生奇怪的值,但你现在得到有用的值.volumeAvailableCapacityForImportantUsageKey
and .volumeAvailableCapacityForOpportunisticUsageKey
.
Example:
let f = ByteCountFormatter()
let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
print("path = \(path)")
let attrs = try! FileManager.default.attributesOfFileSystem(forPath: path)
let fmFree = (attrs[.systemFreeSize] as! NSNumber).int64Value
print("FileManager.attributesOfFileSystem free: \(f.string(fromByteCount: fmFree))")
let docsURL = URL(fileURLWithPath: path)
let values = try! docsURL.resourceValues(forKeys: [.volumeAvailableCapacityKey, .volumeAvailableCapacityForImportantUsageKey, .volumeAvailableCapacityForOpportunisticUsageKey])
print("Volume available capacity: \(f.string(fromByteCount: Int64(values.volumeAvailableCapacity!)))")
print("Volume important available capacity: \(f.string(fromByteCount: values.volumeAvailableCapacityForImportantUsage!))")
print("Volume opportunistic available capacity: \(f.string(fromByteCount: Int64(values.volumeAvailableCapacityForOpportunisticUsage!)))")
在我的系统上打印:
FileManager.attributesOfFileSystem free: 8.51 GB
Volume available capacity: 8.51 GB
Volume important available capacity: 177.16 GB
Volume opportunistic available capacity: 175.88 GB
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