Should l I use [unowned self] for Realm.write()?

Question

I have some weird memory issues in an app and I'm wondering if I'm doing the correct thing here. I use Realm and have eg:

try! self.realm.write {
    self.realm.add(newItem)
}

But I'm wondering if I'm causing a retain cycle inadvertently so should maybe do:

try! self.realm.write { [unowned self] in
    self.realm.add(newItem)
}

Which would be correct and why?

Answer 1

If you have a look at the write method declaration, you will see, that the closure is non escaping. So, you don't need to use neither weak nor unowned . It will not lead to retain cycle.

public func write(_ block: (() throws -> Void)) throws {
    beginWrite()
    do {
        try block()
    } catch let error {
        if isInWriteTransaction { cancelWrite() }
        throw error
    }
    if isInWriteTransaction { try commitWrite() }
}

Answer 2

Without knowing much about realm I would suggest using weak self in case that self might be nil.

try! self.realm.write { [weak self] in
    self?.realm.add(newItem)
}

and maybe try to avoid using ! for the try part and instead handle a possible error case properly.