[swift-users] Dictionary with optional values

Artyom Goncharov swift-users_me at mayerscraft.com
Wed May 18 05:56:40 CDT 2016

Hi, here is the playground snippet:

var noOptDict = ["one": 1, "two": 2, "three": 3 ]
noOptDict["one"] = nil
noOptDict // “one” is gone

var optDict: [String: Int?] = ["one": 1, "two": 2, "three": nil]
optDict["one"] = nil
optDict // “one” is gone but “three” is still there

So the first dict instance works as it should, the second using opt values allows to store nil but deletes the key when you assign nil. Is it bug, feature, or both?

Best wishes,

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