[英]How To Get HTML source from URL with Swift
I need to look at the HTML of a page given by a certain URL. 我需要查看某个URL给出的页面的HTML。 If I have this, what is the most efficient and synchronous way to get the HTML source for that URL using Swift?
如果我有这个,使用Swift获取该URL的HTML源代码的最有效和同步方法是什么? I haven't been able to find a concise way online that returns it into a variable as opposed to printing it in a completionHandler.
我无法在线找到一种简洁的方法,将其返回到变量中,而不是在completionHandler中打印它。
I need to manipulate the source outside of whatever call uses the URL. 我需要在任何使用URL的调用之外操纵源代码。 How is this done in Swift?
这是如何在Swift中完成的?
Disclaimer : Since this is getting quite a lot of views, I just want to remind everyone that this answer here is synchronous, and will block your app if you do it on the main thread. 免责声明:由于这获得了很多观点,我只想提醒大家,这里的答案是同步的,并且如果你在主线程上这样做会阻止你的应用。 You should always do this asynchronously (in a background thread), but the question asked for a synchronous method, so it would be out of scope to explain how to do it here.
您应该始终异步执行此操作(在后台线程中),但问题是同步方法,因此在此处解释如何执行此操作将超出范围。
You should probably look at the method : 你应该看一下这个方法:
+ stringWithContentsOfURL:encoding:error
( docs ) + stringWithContentsOfURL:encoding:error
( docs )
You would call it like this in Objective C : 你可以在Objective C中这样称呼它:
NSString *myURLString = @"http://google.com";
NSURL *myURL = [NSURL URLWithString:myURLString];
NSError *error = nil;
NSString *myHTMLString = [NSString stringWithContentsOfURL:myURL encoding: NSUTF8StringEncoding error:&error];
if (error != nil)
{
NSLog(@"Error : %@", error);
}
else
{
NSLog(@"HTML : %@", myHTMLString);
}
So in Swift 3 and 4, the equivalent would be : 所以在Swift 3和4中,等效的是:
let myURLString = "https://google.com"
guard let myURL = URL(string: myURLString) else {
print("Error: \(myURLString) doesn't seem to be a valid URL")
return
}
do {
let myHTMLString = try String(contentsOf: myURL, encoding: .ascii)
print("HTML : \(myHTMLString)")
} catch let error {
print("Error: \(error)")
}
You might want to adapt the encoding (see the constants ) depending on which encoding your page's using. 您可能希望根据页面使用的编码调整编码(请参阅常量 )。
Old answer, Swift 2.2 : 老答案,Swift 2.2:
let myURLString = "http://google.com"
guard let myURL = NSURL(string: myURLString) else {
print("Error: \(myURLString) doesn't seem to be a valid URL")
return
}
do {
let myHTMLString = try String(contentsOfURL: myURL)
print("HTML : \(myHTMLString)")
} catch let error as NSError {
print("Error: \(error)")
}
Old answer, Swift 1.2 : 老答案,Swift 1.2:
let myURLString = "http://google.com"
if let myURL = NSURL(string: myURLString) {
var error: NSError?
let myHTMLString = NSString(contentsOfURL: myURL, encoding: NSUTF8StringEncoding, error: &error)
if let error = error {
println("Error : \(error)")
} else {
println("HTML : \(myHTMLString)")
}
} else {
println("Error: \(myURLString) doesn't seem to be a valid URL")
}
Swift 3: 斯威夫特3:
if let url = URL(string: "https://www.google.com/trends/hottrends/atom/hourly") {
do {
let contents = try String(contentsOf: url)
print(contents)
} catch {
// contents could not be loaded
}
} else {
// the URL was bad!
}
An updated @DCMaxx answer to Swift 2.2 : 更新的@DCMaxx对Swift 2.2的回答:
let myURLString = "http://www.yahoo.com"
if let myURL = NSURL(string: myURLString) {
var error: NSError?
let myHTMLString = try! NSString(contentsOfURL: myURL, encoding: NSUTF8StringEncoding)
if let error = error {
print("Error : \(error)")
} else {
print("HTML : \(myHTMLString)")
}
} else {
print("Error: \(myURLString) doesn't URL")
}
more compact functional example 更紧凑的功能实例
let myURLString = "https://google.com"
let myHTMLString = try URL(string: myURLString)
.flatMap { try Data(contentsOf: $0) }
.flatMap { String(data: $0, encoding: .ascii) }
This is the way to go in Swift 2: 这是Swift 2的方法:
let myURLString = "https://duckduckgo.com/"
if let myURL = NSURL(string: myURLString) {
do {
let myHTMLString = try String(contentsOfURL: myURL, encoding: NSUTF8StringEncoding)
print("HTML : \(myHTMLString)")
} catch {
print("Error : \(error)")
}
} else {
print("Error: \(myURLString) doesn't URL")
}
Also as an extra related to previous answers: 另外,作为与以前的答案额外的 :
Note that Swift 2 introduces a new error handling approach that produces much clearer code for programmers to read, it does away with complexities like &
to pass in NSErrors
, and it gives you greater safety by ensuring you catch all errors. 需要注意的是斯威夫特2引入了产生更清晰的代码,程序员阅读一个新的错误处理方法,它具有像复杂摒弃
&
在传递NSErrors
,并确保你抓住所有的错误提供了更大的安全性。
Only use try!
只用
try!
if you are 100% sure that the call won't fail. 如果您100%确定通话不会失败。
Further reading: https://www.hackingwithswift.com/new-syntax-swift-2-error-handling-try-catch 进一步阅读: https : //www.hackingwithswift.com/new-syntax-swift-2-error-handling-try-catch
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