对查询字符串的困惑

Question

我正在使用AlamoFire发出API请求。连接到API非常简单，最大的挑战是查询API。

我正在尝试创建一个查询字符串，如下所示：

https://api-fxtrade.oanda.com/v3/instruments/USD_CAD/candles?price=BA&from=2016-10-17T15%3A00%3A00.000000000Z&granularity=M1

我觉得我已经在互联网上搜索了很多关于这个主题的文档，但都找不到。

有没有人有任何关于查询字符串的资源或建议可以分享？

Answer 1

生成查询字符串的最简单方法是使用URLComponents，它为您处理所有百分比转义：

// Keep the init simple, something that you can be sure won't fail
var components = URLComponents(string: "https://api-fxtrade.oanda.com")!

// Now add the other items to your URL query
components.path = "/v3/instruments/USD_CAD/candles"
components.queryItems = [
    URLQueryItem(name: "price", value: "BA"),
    URLQueryItem(name: "from", value: "2016-10-17T15:00:00.000000000Z"),
    URLQueryItem(name: "granularity", value: "M1")
]

if let url = components.url {
    print(url)
} else {
    print("can't make URL")
}

这是纯Swift，您应该熟悉它。一旦您掌握了基础知识，Alamofire可以为您简化它：

let params = [
    "price": "BA",
    "from": "2016-10-17T15:00:00.000000000Z",
    "granularity": "M1"
]
Alamofire.request("https://api-fxtrade.oanda.com/v3/instruments/USD_CAD/candles", parameters: params)
    .responseData { response in
        // Handle response
    }