Moving to Swift 4, I'm running into an issue for which I can't seem to find an
answer in google:
"Cannot use mutating member on immutable value: 'self' is immutable"
The code looks like:
class
ModelFetcher : NSObject, URLSessionDelegate
{
...
static let managerDispatchQueue =
DispatchQueue(label: "Model Download Manager Queue")
static var pendingFetchers = [ModelFetcher]()
static var currentFetcher: ModelFetcher?
class
func
startNextFetcher()
{
self.managerDispatchQueue.async
{
guard
self.currentFetcher == nil,
let mf = self.pendingFetchers.popFirst()
~~~~ ^ error: cannot use
mutating member on immutable value: 'self' is immutable
else
{
return
}
self.currentFetcher = mf
mf.start()
}
}
...
}
This code compiled fine in Xcode 8, or in Xcode 9/Swift 3.2 as a monolithic app
(the error shows up when this code is factored into a framework). Other
mutating references to self seem to compile okay (e.g. "self.currentFetcher =
nil" or "self.pendingFetchers.remove(at: idx)"). Not sure what's special about
this one.
--
Rick Mann
[email protected]
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