常用场景:使用global queue完成操作后切换到main queue更新UI
DispatchQueue.global().async {
//code
DispatchQueue.main.async {
//update ui
}
}
使用Custom Queue
let serialQueue = DispatchQueue(label: "com.serialQueue.dispatch")
let concurrentQueue = DispatchQueue(label: "com.concurrentQueue.dispatch", qos: .background, attributes:.concurrent)
延迟调用
let delay = DispatchTime.now() + DispatchTimeInterval.seconds(3)
DispatchQueue.main.asyncAfter(deadline: delay) {
print("delay 3 seconds")
}
使用Group管理多个Queue,可以使用notify等到结束通知,使用wait等待group中所有操作执行完毕
let group = DispatchGroup()
let bookQueue = DispatchQueue(label: "com.group.book")
bookQueue.async(group: group) {
//down load books
}
let videoQueue = DispatchQueue(label: "com.group.video")
videoQueue.async(group: group) {
//down load videos
}
group.notify(queue: DispatchQueue.main) {
//download finished
}
group.wait()
DispatchWorkItem代替了原先的dispatch_block_t
let workItem = DispatchWorkItem {
//work item
}
DispatchQueue.global().async(execute: workItem)
GCD Timer
let myQueueTimer = DispatchQueue(label: "myQueueTimer", attributes: .concurrent)
let myTimer = DispatchSource.makeTimerSource(queue: myQueueTimer)
myTimer.scheduleRepeating(wallDeadline: DispatchWallTime.now(), interval: .seconds(1))
myTimer.setEventHandler {
//TODO
}
myTimer.resume()
总结:
Swift 3.0中,GCD更加面向对象化,增强了可读性和易用性
网友评论