How to pass and get multiple URLQueryItems in Swif

问题:

Ok, I am working in an iMessage app and am trying to parse more than 1 url query item from the selected message here- I have been successful getting/sending just 1 value in a query:

override func willBecomeActive(with conversation: MSConversation) {
        // Called when the extension is about to move from the inactive to active state.
        // This will happen when the extension is about to present UI.

        if(conversation.selectedMessage?.url != nil) //trying to catch error
        {
            let components = URLComponents(string: (conversation.selectedMessage?.url?.query?.description)!)

            //let val = conversation.selectedMessage?.url?.query?.description
            if let queryItems = components?.queryItems {
                // process the query items here...
                let param1 = queryItems.filter({$0.name == "theirScore"}).first
                print("***************=>    GOT IT ",param1?.value)
            }
        }

When I just have 1 value, just by printing conversation.selectedMessage?.url?.query?.description I get an optional with that 1 value, which is good. But with multiple I cant find a clean way to get specific values by key.

What is the correct way to parse a URLQueryItem for given keys for iMessage?

回答1:

When you do conversation.selectedMessage?.url?.query?.description it simply prints out the contents of the query. If you have multiple items then it would appear something like:

item=Item1&part=Part1&story=Story1

You can parse that one manually by splitting the string on "&" and then splitting the contents of the resulting array on "=" to get the individual key value pairs in to a dictionary. Then, you can directly refer to each value by key to get the specific values, something like this:

var dic = [String:String]()
if let txt = url?.query {
    let arr = txt.components(separatedBy:"&")
    for item in arr {
        let arr2 = item.components(separatedBy:"=")
        let key = arr2[0]
        let val = arr2[1]
        dic[key] = val
    }
}
print(dic)

The above gives you an easy way to access the values by key. However, that is a bit more verbose. The way you provided in your code, using a filter on the queryItems array, is the more compact solution :) So you already have the easier/compact solution, but if this approach makes better sense to you personally, you can always go this route ...

Also, if the issue is that you have to write the same filtering code multiple times to get a value from the queryItems array, then you can always have a helper method which takes two parameters, the queryItems array and a String parameter (the key) and returns an optional String value (the value matching the key) along the following lines:

func valueFrom(queryItems:[URLQueryItem], key:String) -> String? {
    return queryItems.filter({$0.name == key}).first?.value
}

Then your above code would look like:

if let queryItems = components?.queryItems {
    // process the query items here...
    let param1 = valueFrom(queryItems:queryItems, key:"item")
    print("***************=>    GOT IT ", param1)
}

回答2:

You can use iMessageDataKit library. It makes setting and getting data really easy and straightforward like:

let message: MSMessage = MSMessage()

message.md.set(value: 7, forKey: "user_id")
message.md.set(value: "john", forKey: "username")
message.md.set(values: ["joy", "smile"], forKey: "tags")

print(message.md.integer(forKey: "user_id")!)
print(message.md.string(forKey: "username")!)
print(message.md.values(forKey: "tags")!)

(Disclaimer: I'm the author of iMessageDataKit)