如果我想检查我的iPhone上是否存在该文件,请使用以下代码:
let filePath = fileName.path
let fileManager = FileManager.default
if fileManager.fileExists (atPath: filePath) {
}
如何检查网址上是否有pdf / jpg / png文件: www.myname.com/files/file1.jpg或www.myname.com/files/file2.pdf等。
我可以请一个这样的功能的例子 - 但是对于互联网网络服务器上的文件吗?
更新
func remoteFileExistsAt(url: URL, completion: @escaping (Bool) -> Void) {
let checkSession = URLSession.shared
var request = URLRequest(url: url)
request.httpMethod = "HEAD"
request.timeoutInterval = 1.0 // Adjust to your needs
let task = checkSession.dataTask(with: request) { (data, response, error) -> Void in
if let httpResp = response as? HTTPURLResponse {
completion(httpResp.statusCode == 200)
}
}
task.resume()
}
是否可以检查此功能文件是JPG还是PNG类型?如果是这样 - 那么我们也会返回true,如果不是,那么是假的吗?
答案 0 :(得分:2)
在对评论部分进行讨论之后,代码会更新以更正确的方式工作。
您应该检查mimeType
对象的URLResponse
,而不是检查图片是否可以表示为UIImageJPEGRepresentation
/ UIImagePNGRepresentation
。因为它并不能保证资源实际上是 jpg / jpeg 或 png 。
所以mimeType
应该是这里需要考虑的最可靠的参数。
enum MimeType: String {
case jpeg = "image/jpeg"
case png = "image/png"
}
func remoteResource(at url: URL, isOneOf types: [MimeType], completion: @escaping ((Bool) -> Void)) {
var request = URLRequest(url: url)
request.httpMethod = "HEAD"
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
guard let response = response as? HTTPURLResponse, response.statusCode == 200, let mimeType = response.mimeType else {
completion(false)
return
}
if types.map({ $0.rawValue }).contains(mimeType) {
completion(true)
} else {
completion(false)
}
}
task.resume()
}
验证:
let jpegImageURL = URL(string: "https://vignette.wikia.nocookie.net/wingsoffire/images/5/54/Panda.jpeg/revision/latest?cb=20170205005103")!
remoteResource(at: jpegImageURL, isOneOf: [.jpeg, .png]) { (result) in
print(result) // true
}
let pngImageURL = URL(string: "https://upload.wikimedia.org/wikipedia/commons/6/69/Giant_panda_drawing.png")!
remoteResource(at: pngImageURL, isOneOf: [.jpeg, .png]) { (result) in
print(result) //true
}
let gifImageURL = URL(string: "https://media1.tenor.com/images/f88f6514b1a800bae53a8e95b7b99172/tenor.gif?itemid=4616586")!
remoteResource(at: gifImageURL, isOneOf: [.jpeg, .png]) { (result) in
print(result) //false
}
您可以检查远程数据是否可以表示为UIImageJPEGRepresentation
或UIImagePNGRepresentation
。如果是,您可以说远程文件是 JPEG 或 PNG 。
试试这个:
func remoteResource(at url: URL, isImage: @escaping ((Bool) -> Void)) {
let request = URLRequest(url: url)
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
if let data = data, let image = UIImage(data: data) {
if let _ = UIImageJPEGRepresentation(image, 1.0) {
isImage(true)
} else if let _ = UIImagePNGRepresentation(image) {
isImage(true)
} else {
isImage(false)
}
} else {
isImage(false)
}
}
task.resume()
}
<强>用法:强>
let imageURL = URL(string: "http://domaind.com/index.php?action=GET_PHOTO&name=102537.jpg&resolution=FHD&lang=PL®ion=1")!
remoteResource(at: imageURL) { (isImage) in
print(isImage) // prints true for your given link
}
答案 1 :(得分:0)
如果您想知道服务器上存在该文件,则需要发送HTTP请求并接收响应。
请尝试使用以下代码
func remoteFileExistsAt(url: URL, completion: @escaping (Bool) -> Void) {
let checkSession = URLSession.shared
var request = URLRequest(url: url)
request.httpMethod = "HEAD"
request.timeoutInterval = 1.0 // Adjust to your needs
let task = checkSession.dataTask(with: request) { (data, response, error) -> Void in
if let httpResp = response as? HTTPURLResponse {
completion(httpResp.statusCode == 200)
} else {
completion(false)
}
}
task.resume()
}
<强>更新强>
remoteFileExistsAt(url: URL(string: "http://domaind.com/index.php?action=GET_PHOTO&name=102537.jpg&resolution=FHD&lang=PL®ion=1")!) { (success) in
print(success)
}
答案 2 :(得分:0)
这是关于从URL获取数据。如果数据为nil,则文件不存在。