SwiftUI - 加载网络数据

本文分别通过 Observation(iOS17以上) 以及 Combine(iOS17以下) 框架，实现 SwiftUI 的网络数据加载

通过定义 isLoading、error、users 在网络获取的不同阶段按需显示View
isLoading：是否转圈，显示 ProgressView
error：网络获取错误，通过 Text 显示
users：网络获取正常，通过 NavigationStack 显示

Observable

Observable 通过 async await 方式实现

关键代码

func loadData() async {
    let (data, _) = try await URLSession.shared.data(from: url)
    isLoading = false
    
    
    do {
        let decoder = JSONDecoder()
        let reponse = try decoder.decode([User].self, from: data)
        self.users = reponse
        print("reponse success: users")
    } catch {
        print("reponse error1: \(error)")
    }
}

Combine

Combine 通过 Publish 发布实现

关键代码

let publisher = URLSession.shared.dataTaskPublisher(for: url)

publisher
.decode(type: [User].self, decoder: JSONDecoder())
.receive(on: DispatchQueue.main)
.map { users in
    print("publisher map")
    self.users = users
}
.catch { error in
    print("publisher catch")
    return Just(self).map { dataModel in
        dataModel.isLoading = false
        dataModel.error = error
    }
}
.eraseToAnyPublisher()

其他

具体代码：https://github.com/nicaho/LoadDataDemo
参考：https://www.hackingwithswift.com/guide/ios-swiftui/5/3/challenge