Swift 執(zhí)行異步代碼框架 BrightFutures。

我們經(jīng)常會(huì)遇到寫(xiě)異步代碼的情況，比如在等待網(wǎng)絡(luò)響應(yīng)后更新UI，或者在要執(zhí)行耗時(shí)很長(zhǎng)的運(yùn)算后更新UI，通常我們會(huì)寫(xiě)類似下面的代碼：

User.logIn(username, password) { user, error in
    if !error {
        Posts.fetchPosts(user, success: { posts in
            // do something with the user's posts
        }, failure: handleError)
    } else {
        handleError(error) // handeError is a custom function to handle errors
    }
}

使用BrightFutures后，代碼將是這樣的：

User.logIn(username,password).flatMap { user in
    Posts.fetchPosts(user)
}.onSuccess { posts in
    // do something with the user's posts
}.onFailure { error in
    // either logging in or fetching posts failed
}