How to send an array of objects to server in Swift?

A typical approach to be followed is to use the Encodable, you'll be able to get the desired JSON string without the need of the tedious manual handling.

First, you should define the struct for the request (and let it conforms to Encodable):

struct RequestFormat: Encodable {
    var startDate: String
    var startTime: String
    var passengerNumber: String
    var typeId: String
    var originName: String
    var destinationName: String
}

then you could directly use it after setting the desired info:

let encoder = JSONEncoder()
// dummy values
let myRequestObject = RequestFormat(startDate: "1/1/2018",
                                    startTime: "8:00PM",
                                    passengerNumber: "2",
                                    typeId: "10",
                                    originName: "Origin Name",
                                    destinationName: "Destination Name")

hence

do {
    let result = try encoder.encode([myRequestObject])
    if let resultString = String(data: result, encoding: .utf8) {
        print(resultString)
    }
} catch {
    print(error)
}

As you can see, the output of logging printing resultString would be:

[{"startTime":"8:00PM","typeId":"10","originName":"Origin Name","startDate":"1/1/2018","destinationName":"Destination Name","passengerNumber":"2"}]

Note that I encoded as an array (try encoder.encode([myRequestObject])), if you are aiming to get a single object, you could simply implement it as:

let result = try encoder.encode(myRequestObject)

Also, you could -obviously- add more that just one object to the encoded array:

let result = try encoder.encode([myRequestObject, myRequestObject2, myRequestObject3])

which myRequestObject, myRequestObject2 and myRequestObject3 are typed as RequestFormat.