ios - 尝试获取 UIDevice.current.identifierForVendor?.uuidString 时崩溃

Question

我在尝试执行时崩溃了:

static func getDeviceUUID() -> String {
        guard let uuid = UIDevice.current.identifierForVendor?.uuidString else {
            assertionFailure("Nil while unwrapping UIDevice.current.identifierForVendor?.uuidString")
            return ""}
            return uuid
    }

错误提示:Thread 9: Fatal error: Nil while unwrapping UIDevice.current.identifierForVendor?.uuidString

但是当我尝试在控制台中注销它时，它说:

 po UIDevice.current.identifierForVendor?.uuidString
▿ Optional<String>
  - some : "39DEFA50-D6A1-4788-BCCC-5E2A28A04C57"

所以，它实际上是有值(value)的。为什么会发生崩溃？

Answer 1

一切正常

func getDeviceUUID() -> String {
        guard let uuid = UIDevice.current.identifierForVendor?.uuidString else {
            assertionFailure("Nil while unwrapping UIDevice.current.identifierForVendor?.uuidString")
            return ""}
        return uuid
    }

print(getDeviceUUID()) //50E6548C-0BB4-4979-8F5F-DFAD422BEB26