Swift 在dispatchGroup中从未调用group.notify
我有小组和队列Swift 在dispatchGroup中从未调用group.notify,swift,concurrency,dispatchgroup,Swift,Concurrency,Dispatchgroup,我有小组和队列 let group = DispatchGroup() let queue = DispatchQueue(label: "downloadImages", attributes: .concurrent) 在我的函数中,我发送3个请求 func getImages() { networkService.getImages(find: film.originalTitle) { [weak self] result in
let group = DispatchGroup()
let queue = DispatchQueue(label: "downloadImages", attributes: .concurrent)
在我的函数中,我发送3个请求
func getImages() {
networkService.getImages(find: film.originalTitle) { [weak self] result in
guard let self = self else { return }
self.queue.async(group: self.group) {
switch result {
case let .success(posters):
guard let unwrappedPostersResult = posters?.results else { return }
self.posters?.append(contentsOf: unwrappedPostersResult)
case let .failure(error):
self.view?.failure(error: error)
}
}
}
networkService.getImages(find: film.originalLanguage) { [weak self] result in
guard let self = self else { return }
self.queue.async(group: self.group) {
switch result {
case let .success(posters):
guard let unwrappedPostersResult = posters?.results else { return }
self.posters?.append(contentsOf: unwrappedPostersResult)
case let .failure(error):
self.view?.failure(error: error)
}
}
}
networkService.getImages(find: "movies") { [weak self] result in
guard let self = self else { return }
self.queue.async(group: self.group) {
switch result {
case let .success(posters):
guard let unwrappedPostersResult = posters?.results else { return }
self.posters?.append(contentsOf: unwrappedPostersResult)
case let .failure(error):
self.view?.failure(error: error)
}
}
}
它们工作得很好,但当我添加DispatchGroup时,从未调用过
group.notify(queue: .main) { [weak self] in
guard let self = self else { return }
self.view?.success()
}
完成请求后如何调用group.notify()?创建DispatchGroup()时,需要为所有网络服务添加group.enter()和group.leave()
let group = DispatchGroup()
let queue = DispatchQueue(label: "downloadImages", attributes: .concurrent)
// Enter group
group.enter()
networkService.getImages(find: film.originalTitle) { [weak self] result in
guard let self = self else { return }
self.queue.async(group: self.group) {
switch result {
case let .success(posters):
guard let unwrappedPostersResult = posters?.results else { return }
self.posters?.append(contentsOf: unwrappedPostersResult)
// leave group
group.leave()
case let .failure(error):
self.view?.failure(error: error)
// leave group
group.leave()
}
}
}