属性 访问期间的 ARC 生命周期
ARC lifetime during property access
假设我有两个 类 和两个这样的函数:
public class DataContainer {
let someData = NSMutableData()
}
public class SuperContainer {
let someDataContainer = DataContainer()
}
func subFunc(someDataContainer: DataContainer) {
// Is someSuperContainer guaranteed to be alive?
// Or may it have been released and only someDataContainer is still alive,
// because someSuperContainer is not referenced anymore?
... do something with someDataContainer ...
}
func superFunc() {
let someSuperContainer = SuperContainer()
subFunc(someSuperContainer.someDataContainer)
}
someSuperContainer
是否保证在 subFunc
returns 之前仍然存在,或者它可能会在输入 subFunc
之后因为不再被引用而被释放?
编辑:
更好的例子(我试图让问题保持通用,但现在我认为最好包括一个真实世界的例子):
public class DataContainer {
let someData = NSMutableData()
deinit {
memset_s(someData.mutableBytes, someData.length, 0x00, someData.length)
}
}
func doSomethingWithData(data: NSMutableData) {
// Is DataContainer guaranteed to be still alive?
// Or may it have been released and `data` zeroed-out,
// because someSuperContainer is not referenced anymore
// (and was deinitialized and released)?
... do something with data ...
}
func someFunc() {
let dataContainer = DataContainer()
doSomethingWithData(dataContainer.someData)
}
任何变量或 class 在其作用域结束之前都可用且有效。在您的例子中,someSuperContainer 的范围是 superFunc。当 superFunc 结束时,someSuperContainer 也会结束。
func superFunc() {
let someSuperContainer = SuperContainer()
subFunc(someSuperContainer.someDataContainer)
// someSuperContainer will cease to exist once this func completes.
}
假设我有两个 类 和两个这样的函数:
public class DataContainer {
let someData = NSMutableData()
}
public class SuperContainer {
let someDataContainer = DataContainer()
}
func subFunc(someDataContainer: DataContainer) {
// Is someSuperContainer guaranteed to be alive?
// Or may it have been released and only someDataContainer is still alive,
// because someSuperContainer is not referenced anymore?
... do something with someDataContainer ...
}
func superFunc() {
let someSuperContainer = SuperContainer()
subFunc(someSuperContainer.someDataContainer)
}
someSuperContainer
是否保证在 subFunc
returns 之前仍然存在,或者它可能会在输入 subFunc
之后因为不再被引用而被释放?
编辑: 更好的例子(我试图让问题保持通用,但现在我认为最好包括一个真实世界的例子):
public class DataContainer {
let someData = NSMutableData()
deinit {
memset_s(someData.mutableBytes, someData.length, 0x00, someData.length)
}
}
func doSomethingWithData(data: NSMutableData) {
// Is DataContainer guaranteed to be still alive?
// Or may it have been released and `data` zeroed-out,
// because someSuperContainer is not referenced anymore
// (and was deinitialized and released)?
... do something with data ...
}
func someFunc() {
let dataContainer = DataContainer()
doSomethingWithData(dataContainer.someData)
}
任何变量或 class 在其作用域结束之前都可用且有效。在您的例子中,someSuperContainer 的范围是 superFunc。当 superFunc 结束时,someSuperContainer 也会结束。
func superFunc() {
let someSuperContainer = SuperContainer()
subFunc(someSuperContainer.someDataContainer)
// someSuperContainer will cease to exist once this func completes.
}