我在Swift 2中有很多代码。X(甚至1.x)项目，看起来像这样:
// Move to a background thread to do some long running work
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
let image = self.loadOrGenerateAnImage()
// Bounce back to the main thread to update the UI
dispatch_async(dispatch_get_main_queue()) {
self.imageView.image = image
}
}
或者类似这样的东西来延迟执行:
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(0.5 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
print("test")
}
或任何其他类型的大中央调度API的使用…
现在我已经在Xcode 8(测试版)中为Swift 3打开了我的项目，我得到了各种各样的错误。他们中的一些人愿意修复我的代码，但并不是所有的修复都能产生工作代码。我该怎么办?
Swift 4.1和5。我们在代码中的许多地方都使用了队列。因此，我创建了带有所有队列的Threads类。如果不想使用Threads类，可以从类方法中复制所需的队列代码。
class Threads {
static let concurrentQueue = DispatchQueue(label: "AppNameConcurrentQueue", attributes: .concurrent)
static let serialQueue = DispatchQueue(label: "AppNameSerialQueue")
// Main Queue
class func performTaskInMainQueue(task: @escaping ()->()) {
DispatchQueue.main.async {
task()
}
}
// Background Queue
class func performTaskInBackground(task:@escaping () throws -> ()) {
DispatchQueue.global(qos: .background).async {
do {
try task()
} catch let error as NSError {
print("error in background thread:\(error.localizedDescription)")
}
}
}
// Concurrent Queue
class func perfromTaskInConcurrentQueue(task:@escaping () throws -> ()) {
concurrentQueue.async {
do {
try task()
} catch let error as NSError {
print("error in Concurrent Queue:\(error.localizedDescription)")
}
}
}
// Serial Queue
class func perfromTaskInSerialQueue(task:@escaping () throws -> ()) {
serialQueue.async {
do {
try task()
} catch let error as NSError {
print("error in Serial Queue:\(error.localizedDescription)")
}
}
}
// Perform task afterDelay
class func performTaskAfterDealy(_ timeInteval: TimeInterval, _ task:@escaping () -> ()) {
DispatchQueue.main.asyncAfter(deadline: (.now() + timeInteval)) {
task()
}
}
}
显示主队列使用的示例。
override func viewDidLoad() {
super.viewDidLoad()
Threads.performTaskInMainQueue {
//Update UI
}
}
