转换为Swift3错误

在将Xcode转换为Swift 3.0语法后，我发现以下错误：

错误：无法使用类型为“（qos_class_t）”的参数列表调用类型为“Int”的初始值设定项 全局（优先级：Int（DispatchQoS.QoSClass.userInitiated.rawValue））.async{ ^

注意：“Int”的重载存在于这些部分匹配的参数列表中：（Int64），（Word），（UInt8），（Int8），（UInt16），（UInt32），（UInt64），（UInt），（Int），（Float），（Double），（Float80），（字符串，基数：Int），（CGFloat），（NSNumber） {DispatchQueue.global（优先级：Int（DispatchQoS.QoSClass.userInitiated.rawValue））.async{

转换后的语法：

func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {

    if searchText == "" {
        self.filteredSymbols = self.symbols
        self.alphabeticSymbolCollection.reloadData()
    } else {
        DispatchQueue.global(priority: Int(DispatchQoS.QoSClass.userInitiated.rawValue)).async {
            let fs = self.filterContentForSearchText(searchText)
            DispatchQueue.main.async {
                self.filteredSymbols = fs

                self.searchActive = true

                self.alphabeticSymbolCollection.reloadData()
            }
        }
    }

}

func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {

    if searchText == "" {
        self.filteredSymbols = self.symbols
        self.alphabeticSymbolCollection.reloadData()
    } else {
        dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.rawValue), 0)) {
            let fs = self.filterContentForSearchText(searchText)
            dispatch_async(dispatch_get_main_queue()) {
                self.filteredSymbols = fs

                self.searchActive = true

                self.alphabeticSymbolCollection.reloadData()
            }
        }
    }

}

转换前的语法：

func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {

    if searchText == "" {
        self.filteredSymbols = self.symbols
        self.alphabeticSymbolCollection.reloadData()
    } else {
        DispatchQueue.global(priority: Int(DispatchQoS.QoSClass.userInitiated.rawValue)).async {
            let fs = self.filterContentForSearchText(searchText)
            DispatchQueue.main.async {
                self.filteredSymbols = fs

                self.searchActive = true

                self.alphabeticSymbolCollection.reloadData()
            }
        }
    }

}

func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {

    if searchText == "" {
        self.filteredSymbols = self.symbols
        self.alphabeticSymbolCollection.reloadData()
    } else {
        dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.rawValue), 0)) {
            let fs = self.filterContentForSearchText(searchText)
            dispatch_async(dispatch_get_main_queue()) {
                self.filteredSymbols = fs

                self.searchActive = true

                self.alphabeticSymbolCollection.reloadData()
            }
        }
    }

}

这很简单

DispatchQueue.global(qos: .userInitiated).async { }

可能重复的