> On May 18, 2016, at 09:38, Ray Fix via swift-users <swift-users@swift.org> > wrote: > > >> On May 18, 2016, at 3:56 AM, Artyom Goncharov via swift-users >> <swift-users@swift.org> wrote: >> >> var noOptDict = ["one": 1, "two": 2, "three": 3 ] >> noOptDict["one"] = nil > > Wow, interesting. To me this was surprising behavior too. > > The comment for Dictionary subscript says: > > /// Access the value associated with the given key. > /// > /// Reading a key that is not present in `self` yields `nil`. > /// Writing `nil` as the value for a given key erases that key from > /// `self`. > > Which is exactly what it is doing. As the Zhaoxin said, you can use > updateValue (and removeValueForKey) to get better results when dealing with > optional dictionary values.
There’s a bit more discussion of this on the Apple Swift blog: https://developer.apple.com/swift/blog/?id=12 <https://developer.apple.com/swift/blog/?id=12> Jordan
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