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Ios URLComponents.url为零

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Ios URLComponents.url为零,ios,swift,nsurl,nsurlcomponents,Ios,Swift,Nsurl,Nsurlcomponents,我正在尝试使用URLComponents来组成URL，因为这似乎就是它的用途 但是，当我访问组件的url属性时，它是nil 例如 var urlComponents = URLComponents(string: "http://google.com")! urlComponents.path = "auth/login" 那我真的 print(urlComponents) 输出 scheme: http host: google.com path: auth/login - schem

我正在尝试使用
URLComponents
来组成
URL
，因为这似乎就是它的用途

但是，当我访问组件的
url
属性时，它是nil

例如

var urlComponents = URLComponents(string: "http://google.com")!
urlComponents.path = "auth/login"
那我真的

print(urlComponents)
输出

scheme: http host: google.com path: auth/login
  - scheme : "http"
  - host : "google.com"
  - path : "auth/login"
但是

print(urlComponents.url)
输出
nil

我是不是做错了什么？如何从所有这些中获取完整格式的URL？谢谢

它看起来像是
路径
参数的字符串必须以
/
开头

因此，将
“auth/login”
更改为
“/auth/login”
即可；DR

如果您正在创建web URL（例如
http://example.com/path
），包括
/
，因为它使用以下模板：

{scheme}://{user}:{password}@{host}:{port}{path}?{query}#{fragment}

{scheme}:{path}?{query}%23{fragment}
如果您正在创建非web URL（例如，
mailto:user@example.com
），不要包含
/
，因为它使用以下模板：

{scheme}://{user}:{password}@{host}:{port}{path}?{query}#{fragment}

{scheme}:{path}?{query}%23{fragment}
为了阐明发生这种情况的原因，的实际模板如下：

{scheme}://{user}:{password}@{host}:{port}{path}?{query}#{fragment}
请注意，除了
{port}
和
{path}
之外，每两个组件之间都有标点（
：//
，
：
，
），
{port}
和
{path}
）

因此，
{path}
必须以标点符号（
/
）作为前缀，否则将生成无效的URL。

在您的情况下，您必须使用：


urlComponents.path = "/auth/login"




请注意，即使省略URLComponents的不常见字段，也会遇到相同的问题：


{scheme}://{host}{path}?{query}#{fragment}


请注意，在本例中，
{host}
和
{path}
也是相邻的，没有标点符号将两者分开

你可能想知道为什么苹果在
{port}
之前没有添加标点符号。我的猜测是因为URLComponents可以用于生成规范中的任何类型的URL，而不仅仅是Web URL。例如，它可以很容易地生成
http://www.example.com/foo
，但它应该同样容易地生成
mailto格式的URL：user@example.com

当省略
{host}
时，URLComponents通过更改
{scheme}
和
{path}
之间的分隔符来实现这一点：


{scheme}:{path}?{query}%23{fragment}


因此，当我们想要生成mailto链接时，我们实际上不会在路径中包含
/
：


urlComponents.scheme = "mailto"
urlComponents.path = "user@example.com"
// urlComponents.url!.absoluteString == "mailto:user@example.com"




比较URLComponents的属性和URL的属性可以提供更多的洞察力（并揭示出一些不一致性）：

有两点需要注意：


    

  • url.path
    的后缀中没有
    /
    • 

  • url.pathComponents[0]
    是url中的第一个
    /
    • 




要获得模板的详细列表，可以使用以下代码：


let componentsCount = Double(8)
let iterations = Int(pow(2, componentsCount))

for i in 0..<iterations {
  var urlComponents = URLComponents()
  var key = ""
  if i & 0b10000000 > 0 { urlComponents.scheme = "scheme"; key += "s" } else { key += " " }
  if i & 0b01000000 > 0 { urlComponents.user = "user"; key += "u" } else { key += " " }
  if i & 0b00100000 > 0 { urlComponents.password = "password"; key += "w" } else { key += " " }
  if i & 0b00010000 > 0 { urlComponents.host = "host"; key += "h" } else { key += " " }
  if i & 0b00001000 > 0 { urlComponents.port = 123; key += "r" } else { key += " " }
  if i & 0b00000100 > 0 { urlComponents.path = "/path"; key += "p" } else { key += " " }
  if i & 0b00000010 > 0 { urlComponents.query = "query"; key += "q" } else { key += " " }
  if i & 0b00000001 > 0 { urlComponents.fragment = "fragment"; key += "f" } else { key += " " }

  if let url = urlComponents.url?.absoluteString {
    print("[\(key)] \(url)")
  } else {
    print("[\(key)] ------- nil --------")
  }
}


请注意，这些都不是
nil
。但是，如果将
urlComponents.path=“/path”
更改为
urlComponents.path=“path”
，则会得到一组完全不同的模板：


[        ] 
[       f] #fragment
[      q ] ?query
[      qf] ?query#fragment
[     p  ] path
[     p f] path#fragment
[     pq ] path?query
[     pqf] path?query#fragment
[    r   ] //:123
[    r  f] //:123#fragment
[    r q ] //:123?query
[    r qf] //:123?query#fragment
[    rp  ] ------- nil --------
[    rp f] ------- nil --------
[    rpq ] ------- nil --------
[    rpqf] ------- nil --------
[   h    ] //host
[   h   f] //host#fragment
[   h  q ] //host?query
[   h  qf] //host?query#fragment
[   h p  ] ------- nil --------
[   h p f] ------- nil --------
[   h pq ] ------- nil --------
[   h pqf] ------- nil --------
[   hr   ] //host:123
[   hr  f] //host:123#fragment
[   hr q ] //host:123?query
[   hr qf] //host:123?query#fragment
[   hrp  ] ------- nil --------
[   hrp f] ------- nil --------
[   hrpq ] ------- nil --------
[   hrpqf] ------- nil --------
[  w     ] //:password@
[  w    f] //:password@#fragment
[  w   q ] //:password@?query
[  w   qf] //:password@?query#fragment
[  w  p  ] ------- nil --------
[  w  p f] ------- nil --------
[  w  pq ] ------- nil --------
[  w  pqf] ------- nil --------
[  w r   ] //:password@:123
[  w r  f] //:password@:123#fragment
[  w r q ] //:password@:123?query
[  w r qf] //:password@:123?query#fragment
[  w rp  ] ------- nil --------
[  w rp f] ------- nil --------
[  w rpq ] ------- nil --------
[  w rpqf] ------- nil --------
[  wh    ] //:password@host
[  wh   f] //:password@host#fragment
[  wh  q ] //:password@host?query
[  wh  qf] //:password@host?query#fragment
[  wh p  ] ------- nil --------
[  wh p f] ------- nil --------
[  wh pq ] ------- nil --------
[  wh pqf] ------- nil --------
[  whr   ] //:password@host:123
[  whr  f] //:password@host:123#fragment
[  whr q ] //:password@host:123?query
[  whr qf] //:password@host:123?query#fragment
[  whrp  ] ------- nil --------
[  whrp f] ------- nil --------
[  whrpq ] ------- nil --------
[  whrpqf] ------- nil --------
[ u      ] //user@
[ u     f] //user@#fragment
[ u    q ] //user@?query
[ u    qf] //user@?query#fragment
[ u   p  ] ------- nil --------
[ u   p f] ------- nil --------
[ u   pq ] ------- nil --------
[ u   pqf] ------- nil --------
[ u  r   ] //user@:123
[ u  r  f] //user@:123#fragment
[ u  r q ] //user@:123?query
[ u  r qf] //user@:123?query#fragment
[ u  rp  ] ------- nil --------
[ u  rp f] ------- nil --------
[ u  rpq ] ------- nil --------
[ u  rpqf] ------- nil --------
[ u h    ] //user@host
[ u h   f] //user@host#fragment
[ u h  q ] //user@host?query
[ u h  qf] //user@host?query#fragment
[ u h p  ] ------- nil --------
[ u h p f] ------- nil --------
[ u h pq ] ------- nil --------
[ u h pqf] ------- nil --------
[ u hr   ] //user@host:123
[ u hr  f] //user@host:123#fragment
[ u hr q ] //user@host:123?query
[ u hr qf] //user@host:123?query#fragment
[ u hrp  ] ------- nil --------
[ u hrp f] ------- nil --------
[ u hrpq ] ------- nil --------
[ u hrpqf] ------- nil --------
[ uw     ] //user:password@
[ uw    f] //user:password@#fragment
[ uw   q ] //user:password@?query
[ uw   qf] //user:password@?query#fragment
[ uw  p  ] ------- nil --------
[ uw  p f] ------- nil --------
[ uw  pq ] ------- nil --------
[ uw  pqf] ------- nil --------
[ uw r   ] //user:password@:123
[ uw r  f] //user:password@:123#fragment
[ uw r q ] //user:password@:123?query
[ uw r qf] //user:password@:123?query#fragment
[ uw rp  ] ------- nil --------
[ uw rp f] ------- nil --------
[ uw rpq ] ------- nil --------
[ uw rpqf] ------- nil --------
[ uwh    ] //user:password@host
[ uwh   f] //user:password@host#fragment
[ uwh  q ] //user:password@host?query
[ uwh  qf] //user:password@host?query#fragment
[ uwh p  ] ------- nil --------
[ uwh p f] ------- nil --------
[ uwh pq ] ------- nil --------
[ uwh pqf] ------- nil --------
[ uwhr   ] //user:password@host:123
[ uwhr  f] //user:password@host:123#fragment
[ uwhr q ] //user:password@host:123?query
[ uwhr qf] //user:password@host:123?query#fragment
[ uwhrp  ] ------- nil --------
[ uwhrp f] ------- nil --------
[ uwhrpq ] ------- nil --------
[ uwhrpqf] ------- nil --------
[s       ] scheme:
[s      f] scheme:%23fragment
[s     q ] scheme:?query
[s     qf] scheme:?query%23fragment
[s    p  ] scheme:path
[s    p f] scheme:path%23fragment
[s    pq ] scheme:path?query
[s    pqf] scheme:path?query%23fragment
[s   r   ] scheme://:123
[s   r  f] scheme://:123#fragment
[s   r q ] scheme://:123?query
[s   r qf] scheme://:123?query#fragment
[s   rp  ] ------- nil --------
[s   rp f] ------- nil --------
[s   rpq ] ------- nil --------
[s   rpqf] ------- nil --------
[s  h    ] scheme://host
[s  h   f] scheme://host#fragment
[s  h  q ] scheme://host?query
[s  h  qf] scheme://host?query#fragment
[s  h p  ] ------- nil --------
[s  h p f] ------- nil --------
[s  h pq ] ------- nil --------
[s  h pqf] ------- nil --------
[s  hr   ] scheme://host:123
[s  hr  f] scheme://host:123#fragment
[s  hr q ] scheme://host:123?query
[s  hr qf] scheme://host:123?query#fragment
[s  hrp  ] ------- nil --------
[s  hrp f] ------- nil --------
[s  hrpq ] ------- nil --------
[s  hrpqf] ------- nil --------
[s w     ] scheme://:password@
[s w    f] scheme://:password@#fragment
[s w   q ] scheme://:password@?query
[s w   qf] scheme://:password@?query#fragment
[s w  p  ] ------- nil --------
[s w  p f] ------- nil --------
[s w  pq ] ------- nil --------
[s w  pqf] ------- nil --------
[s w r   ] scheme://:password@:123
[s w r  f] scheme://:password@:123#fragment
[s w r q ] scheme://:password@:123?query
[s w r qf] scheme://:password@:123?query#fragment
[s w rp  ] ------- nil --------
[s w rp f] ------- nil --------
[s w rpq ] ------- nil --------
[s w rpqf] ------- nil --------
[s wh    ] scheme://:password@host
[s wh   f] scheme://:password@host#fragment
[s wh  q ] scheme://:password@host?query
[s wh  qf] scheme://:password@host?query#fragment
[s wh p  ] ------- nil --------
[s wh p f] ------- nil --------
[s wh pq ] ------- nil --------
[s wh pqf] ------- nil --------
[s whr   ] scheme://:password@host:123
[s whr  f] scheme://:password@host:123#fragment
[s whr q ] scheme://:password@host:123?query
[s whr qf] scheme://:password@host:123?query#fragment
[s whrp  ] ------- nil --------
[s whrp f] ------- nil --------
[s whrpq ] ------- nil --------
[s whrpqf] ------- nil --------
[su      ] scheme://user@
[su     f] scheme://user@#fragment
[su    q ] scheme://user@?query
[su    qf] scheme://user@?query#fragment
[su   p  ] ------- nil --------
[su   p f] ------- nil --------
[su   pq ] ------- nil --------
[su   pqf] ------- nil --------
[su  r   ] scheme://user@:123
[su  r  f] scheme://user@:123#fragment
[su  r q ] scheme://user@:123?query
[su  r qf] scheme://user@:123?query#fragment
[su  rp  ] ------- nil --------
[su  rp f] ------- nil --------
[su  rpq ] ------- nil --------
[su  rpqf] ------- nil --------
[su h    ] scheme://user@host
[su h   f] scheme://user@host#fragment
[su h  q ] scheme://user@host?query
[su h  qf] scheme://user@host?query#fragment
[su h p  ] ------- nil --------
[su h p f] ------- nil --------
[su h pq ] ------- nil --------
[su h pqf] ------- nil --------
[su hr   ] scheme://user@host:123
[su hr  f] scheme://user@host:123#fragment
[su hr q ] scheme://user@host:123?query
[su hr qf] scheme://user@host:123?query#fragment
[su hrp  ] ------- nil --------
[su hrp f] ------- nil --------
[su hrpq ] ------- nil --------
[su hrpqf] ------- nil --------
[suw     ] scheme://user:password@
[suw    f] scheme://user:password@#fragment
[suw   q ] scheme://user:password@?query
[suw   qf] scheme://user:password@?query#fragment
[suw  p  ] ------- nil --------
[suw  p f] ------- nil --------
[suw  pq ] ------- nil --------
[suw  pqf] ------- nil --------
[suw r   ] scheme://user:password@:123
[suw r  f] scheme://user:password@:123#fragment
[suw r q ] scheme://user:password@:123?query
[suw r qf] scheme://user:password@:123?query#fragment
[suw rp  ] ------- nil --------
[suw rp f] ------- nil --------
[suw rpq ] ------- nil --------
[suw rpqf] ------- nil --------
[suwh    ] scheme://user:password@host
[suwh   f] scheme://user:password@host#fragment
[suwh  q ] scheme://user:password@host?query
[suwh  qf] scheme://user:password@host?query#fragment
[suwh p  ] ------- nil --------
[suwh p f] ------- nil --------
[suwh pq ] ------- nil --------
[suwh pqf] ------- nil --------
[suwhr   ] scheme://user:password@host:123
[suwhr  f] scheme://user:password@host:123#fragment
[suwhr q ] scheme://user:password@host:123?query
[suwhr qf] scheme://user:password@host:123?query#fragment
[suwhrp  ] ------- nil --------
[suwhrp f] ------- nil --------
[suwhrpq ] ------- nil --------
[suwhrpqf] ------- nil --------



试图使用NSURLComponents而不是URLComponents？您的变量URLComponents中缺少“”。（你代码的第一行）@UmairAfzal我在用Swift。URLComponents桥接到NSURLComponents（根据文档）。@0ndre_uu复制错误。谢谢，我现在编辑了这个问题。我想是的：D。我在文件里翻了一番之后，正要亲自来回答这个问题。（谁会想到文档会解释出哪里出了问题，哈哈！）谢谢我想知道，如果你还需要注意这些事情，那么有一个专门的类型为你构建一个URL（而不是仅仅从scheme、host等手动构建字符串）有什么意义？sheesh…@NicolasMiari它实际上非常有用，可以将查询参数、不同的方案和主机嵌入url等。。。也许在测试和生产主机之间切换……坦克，这真的帮助了我！同样的问题让我抓狂了好几个小时。路径中缺少前面的“/”。