Open Radar

 
When using Swift 2.3, NSJSONSerialization serializes the dictionary ["first": true, "second": false] as:

{"first":true,"second":false}

When using Swift 3.0, JSONSerialization serializes the same dictionary as:

{"first":1,"second":0}

Some web service APIs, including the Gmail API, will reject 1 or 0 when expecting a boolean value.


Steps to reproduce:

1.  In a Swift 2.3 project, run this unit test. It will pass.

    func testJson() {
        
        let inputJsonDictionary = ["first": true, "second": false]
        
        guard let data = try? NSJSONSerialization.dataWithJSONObject(inputJsonDictionary, options: []) else {
            XCTFail()
            return
        }
        
        guard let jsonString = String(data: data, encoding: NSUTF8StringEncoding) else {
            XCTFail()
            return
        }
        print(jsonString)
        XCTAssertTrue(jsonString == "{\"first\":true,\"second\":false}" || jsonString == "{\"second\":false},\"first\":true")
    }

2.  In a Swift 3.0 project, run this unit test

    func testJson() {
        
        let inputJsonDictionary = ["first": true, "second": false]
        
        guard let data = try? JSONSerialization.data(withJSONObject: inputJsonDictionary, options: []) else {
            XCTFail()
            return
        }
        
        guard let jsonString = String(data: data, encoding: String.Encoding.utf8) else {
            XCTFail()
            return
        }
        print(jsonString)
        XCTAssertTrue(jsonString == "{\"first\":true,\"second\":false}" || jsonString == "{\"second\":false},\"first\":true")
    }
    

Expected Results:

I would expect the Swift 3.0 unit test to pass.


Actual Results:

The Swift 3.0 unit test fails. The value of jsonString is:

{"first":1,"second":0}  - or -  {"second":0,"first":1}


Configuration:

I encountered this using Xcode 8.0 beta 6 while developing an iOS app. I can reproduce the bug both on the simulator and on an iPod Touch running iOS 10 beta 7 (14A5345a). I am not certain, but I believe this is a change in behavior since Xcode 8.0 beta 5.

Additional Notes:

I think this is an important bug. Many app developers write apps that talk to web services outside of their control.

Thank you for taking a look.