转换为 Swift3 错误

Question

Xcode 转换为 Swift 3.0 语法后，出现以下错误：

错误：无法使用类型为“（qos_class_t）”的参数列表调用类型“Int”的初始化程序 DispatchQueue.global(优先级：Int(DispatchQoS.QoSClass.userInitiated.rawValue)).async { ^

注意：“Int”的重载存在这些部分匹配的参数列表：(Int64)、(Word)、(UInt8)、(Int8)、(UInt16)、(Int16)、(UInt32)、(Int32)、 (UInt64), (UInt), (Int), (Float), (Double), (Float80), (String, radix: Int), (CGFloat), (NSNumber) {DispatchQueue.global(priority: 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()
            }
        }
    }

}

转换前的语法：

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()
            }
        }
    }

}

Answer 1

很简单

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