Swift开发中如何等待CLGeocoder逆地理编码执行完成？

核心原因 #

CLGeocoder的reverseGeocodeLocation本身是异步API，内部会在系统队列执行网络/本地查询逻辑，直接把函数调用放到同步队列也不会等待回调执行，所以之前的方案不生效。

方案1：闭包回调（全系统版本兼容，最常用） #

把原函数改造为带完成回调的形式，后续逻辑直接放到回调内部执行即可，同时修复原代码强制解包可能导致的崩溃问题：

private func getAddressFromLocation(forLocation: CLLocationCoordinate2D, completion: @escaping (String?) -> Void) {
    let geoCoder = CLGeocoder()
    geoCoder.reverseGeocodeLocation(CLLocation(latitude: forLocation.latitude, longitude: forLocation.longitude), completionHandler: {(places, error) in
        guard error == nil, let place = places?.first else {
            completion(nil)
            return
        }
        var address: [String] = []
        if let country = place.country { address.append(country) }
        if let postalCode = place.postalCode { address.append(postalCode) }
        if let locality = place.locality { address.append(locality) }
        if let thoroughfare = place.thoroughfare { address.append(thoroughfare) }
        let fullAddress = address.joined(separator: ",")
        self.fullAddress = fullAddress
        completion(fullAddress)
    })
}

调用示例：

// 调用位置
getAddressFromLocation(forLocation: 需要解析的坐标) { [weak self] address in
    guard let self = self, let address = address else {
        // 处理解析失败的逻辑
        return
    }
    // 地址赋值完成，后续逻辑写在这里
    print("已获取地址: \(address)")
}

方案2：Async/Await（iOS 15+ 推荐） #

如果你的App最低支持iOS 15，用Swift原生的异步写法逻辑更清晰，避免回调嵌套：
改造后的函数：

@available(iOS 15.0, *)
private func getAddressFromLocation(forLocation: CLLocationCoordinate2D) async throws -> String {
    let geoCoder = CLGeocoder()
    let places = try await geoCoder.reverseGeocodeLocation(CLLocation(latitude: forLocation.latitude, longitude: forLocation.longitude))
    guard let place = places.first else {
        throw NSError(domain: "GeocodeError", code: -1, userInfo: [NSLocalizedDescriptionKey: "未匹配到地址信息"])
    }
    var address: [String] = []
    if let country = place.country { address.append(country) }
    if let postalCode = place.postalCode { address.append(postalCode) }
    if let locality = place.locality { address.append(locality) }
    if let thoroughfare = place.thoroughfare { address.append(thoroughfare) }
    let fullAddress = address.joined(separator: ",")
    self.fullAddress = fullAddress
    return fullAddress
}

调用示例：

Task {
    do {
        let address = try await getAddressFromLocation(forLocation: 需要解析的坐标)
        // 地址赋值完成，后续逻辑写在这里
        print("已获取地址: \(address)")
    } catch {
        // 处理解析失败逻辑
        print("地址解析失败: \(error.localizedDescription)")
    }
}

不推荐方案：DispatchSemaphore 同步阻塞 #

如果一定要实现同步等待的效果，可以用信号量实现，但绝对不要在主线程调用，否则会阻塞主线程事件循环导致APP无响应：

// 仅可在后台线程调用，主线程调用会卡死
private func getAddressSync(forLocation: CLLocationCoordinate2D) -> String? {
    let semaphore = DispatchSemaphore(value: 0)
    var result: String?
    let geoCoder = CLGeocoder()
    geoCoder.reverseGeocodeLocation(CLLocation(latitude: forLocation.latitude, longitude: forLocation.longitude)) { places, error in
        defer { semaphore.signal() }
        guard error == nil, let place = places?.first else {
            result = nil
            return
        }
        var address: [String] = []
        if let country = place.country { address.append(country) }
        if let postalCode = place.postalCode { address.append(postalCode) }
        if let locality = place.locality { address.append(locality) }
        if let thoroughfare = place.thoroughfare { address.append(thoroughfare) }
        result = address.joined(separator: ",")
        self.fullAddress = result
    }
    semaphore.wait()
    return result
}

内容的提问来源于stack exchange，提问作者Dawy