Swift 3快速异步助手 - Do.this

2016-12-08      31      Swift
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Do.this是一个Swift 3快速异步助手,灵感来自node.js Async。


Do.this { this in

    //do stuff
    this.done(result: someResult)

}.then (name: "result step") { this in

    //do more stuff

    //every this has an index property and an optional name property
    //which can be useful for debugging and error handling
    print("this: \(this.name ?? String(this.index))")

    //you can also access the previous result if needed:
    print("previousResult: \(this.previousResult)")

    //if you're doing anything async, don't forget to call done()   
    DispatchQueue.main.asyncAfter(deadline: .now() + 2) {

        //async stuff

        //btw, result is optional

}.then { this in

    //if an error happened, pass it in the done callback (you can still pass a result)
    //if you pass an error, the chain will break (see catch and finally below)
    let error = SomeError.bummer
    this.done(result: someResult, error: error)

}.then (on: DispatchQueue.global(qos: .background)) { this in

    //this will execute in a background queue
    print("on: \(DispatchQueue.currentLabel)")
    this.done(result: someResult)

}.then (on: .main) { this in

    //this will be execute in the main queue
    //if you dont specify a queue, this will be executed on the current (last used) queue
    print("on: \(DispatchQueue.currentLabel)")
    this.done(result: someResult)

}.catch { this in

    //catch an error, this will point to the step that triggered the error  
    print("catched error: \(this.error) from \(this.name ?? String(this.index))")

}.finally { this in

    //finally - will execute even if an error happened
    print("finally (previousResult: \(this.previousResult))")


Swift 3