集成Tomorrow.io API时的错误处理问题：未捕获抛出错误

你遇到的错误核心原因是：async函数内使用try但未处理抛出的错误，Swift要求所有抛出的错误必须被捕获，或是让函数本身向外传递错误。下面提供两种可行的解决方式：

方式一：用do-catch捕获并处理错误 #

把try await的请求代码包裹在do块中，通过catch捕获网络请求、URL解析等环节可能出现的错误：

import Foundation

func WeatherAPI() async {
    guard let url = URL(string: "https://api.tomorrow.io/v4/weather/forecast") else {
        print("无效的基础URL")
        return
    }
    guard var components = URLComponents(url: url, resolvingAgainstBaseURL: true) else {
        print("无法解析URL组件")
        return
    }
    let queryItems: [URLQueryItem] = [
        URLQueryItem(name: "location", value: "Location..."),
        URLQueryItem(name: "apikey", value: "API Code Not Going to be shown"),
    ]
    components.queryItems = (components.queryItems ?? []) + queryItems
    
    guard let finalURL = components.url else {
        print("无法生成最终请求URL")
        return
    }
    
    var request = URLRequest(url: finalURL)
    request.httpMethod = "GET"
    request.timeoutInterval = 10
    request.allHTTPHeaderFields = [
        "accept": "application/json",
        "accept-encoding": "deflate, gzip, br"
    ]
    
    do {
        let (data, _) = try await URLSession.shared.data(for: request)
        print(String(decoding: data, as: UTF8.self))
    } catch {
        print("请求失败：\(error.localizedDescription)")
        // 这里还可以根据错误类型做针对性处理，比如判断是否是网络超时、无网络连接等
    }
}

方式二：让函数向外抛出错误 #

如果希望由调用该函数的地方处理错误，可以将函数声明为throws async，把错误传递给调用者：

import Foundation

func WeatherAPI() async throws {
    guard let url = URL(string: "https://api.tomorrow.io/v4/weather/forecast") else {
        throw NSError(domain: "WeatherAPI", code: 1, userInfo: [NSLocalizedDescriptionKey: "无效的基础URL"])
    }
    guard var components = URLComponents(url: url, resolvingAgainstBaseURL: true) else {
        throw NSError(domain: "WeatherAPI", code: 2, userInfo: [NSLocalizedDescriptionKey: "无法解析URL组件"])
    }
    let queryItems: [URLQueryItem] = [
        URLQueryItem(name: "location", value: "Location..."),
        URLQueryItem(name: "apikey", value: "API Code Not Going to be shown"),
    ]
    components.queryItems = (components.queryItems ?? []) + queryItems
    
    guard let finalURL = components.url else {
        throw NSError(domain: "WeatherAPI", code: 3, userInfo: [NSLocalizedDescriptionKey: "无法生成最终请求URL"])
    }
    
    var request = URLRequest(url: finalURL)
    request.httpMethod = "GET"
    request.timeoutInterval = 10
    request.allHTTPHeaderFields = [
        "accept": "application/json",
        "accept-encoding": "deflate, gzip, br"
    ]
    
    let (data, _) = try await URLSession.shared.data(for: request)
    print(String(decoding: data, as: UTF8.self))
}

// 调用示例：
// do {
//     try await WeatherAPI()
// } catch {
//     print("处理错误：\(error)")
// }

额外提醒：原代码中的!强制解包风险很高，一旦URL或组件解析失败会直接导致崩溃，上面的代码用guard let替换了强制解包，提升了代码的稳定性。

内容的提问来源于stack exchange，提问作者Train Lover