ios 检查 URL 是否有 http:// 前缀

Check if an URL has got http:// prefix

提问by matteodv

In my application, when the user add an object, can also add a link for this object and then the link can be opened in a webView.
I tried to save a link without http:// prefix, then open it in the webView but that can't open it!
Before webView starts loading, is there a method to check if the URL saved has got http:// prefix? And if it hasn't got it, how can I add the prefix to the URL?
Thanks!

在我的应用程序中，当用户添加一个对象时，也可以为这个对象添加一个链接，然后可以在一个 webView 中打开该链接。
我试图保存一个没有 http:// 前缀的链接，然后在 webView 中打开它，但无法打开它！
在 webView 开始加载之前，有没有办法检查保存的 URL 是否有 http:// 前缀？如果它没有得到它，我如何将前缀添加到 URL 中？
谢谢！

回答by Greg

You can use the - (BOOL)hasPrefix:(NSString *)aStringmethod on NSString to see if an NSString containing your URL starts with the http:// prefix, and if not add the prefix.

您可以使用- (BOOL)hasPrefix:(NSString *)aStringNSString 上的方法查看包含您的 URL 的 NSString 是否以 http:// 前缀开头，如果没有添加前缀。

NSString *myURLString = @"www.google.com";
NSURL *myURL;
if ([myURLString.lowercaseString hasPrefix:@"http://"]) {
    myURL = [NSURL URLWithString:myURLString];
} else {
    myURL = [NSURL URLWithString:[NSString stringWithFormat:@"http://%@",myURLString]];
}

I'm currently away from my mac and can't compile/test this code, but I believe the above should work.

我目前不在我的 mac 上，无法编译/测试此代码，但我相信上述内容应该可行。

回答by tc.

NSString * urlString = ...;
NSURL * url = [NSURL URLWithString:urlString];
if (![[url scheme] length])
{
  url = [NSURL URLWithString:[@"http://" stringByAppendingString:urlString]];
}

回答by anoop4real

I wrote an extension for String in Swift, to see if url string got http or https

我在 Swift 中为 String 写了一个扩展，看看 url 字符串是得到 http 还是 https

extension String{

    func isValidForUrl()->Bool{

        if(self.hasPrefix("http") || self.hasPrefix("https")){
            return true
        }
        return false
    }
}

if(urlString.isValidForUrl())
    {
      //Do the thing here.
}

回答by shim

Better to use the schemeproperty on the URLobject:

最好scheme在URL对象上使用该属性：

extension URL {
    var isHTTPScheme: Bool {
        return scheme?.contains("http") == true // or hasPrefix
    }
}

Example usage:

用法示例：

let myURL = https://stackoverflow.com/a/48835119/1032372
if myURL.isHTTPScheme {
    // handle, e.g. open in-app browser:            
    present(SFSafariViewController(url: url), animated: true)
} else if UIApplication.shared.canOpenURL(myURL) {
    UIApplication.shared.openURL(myURL)
}

回答by kthorat

I am not sure if there is any method to check that but you check it in the code.

我不确定是否有任何方法可以检查它，但您可以在代码中检查它。

try using

尝试使用

NSRange range = [urlString rangeOfString:@"http://"];
if (range.location != NSNotFound)
    // Add http://  

回答by bobics

If you're checking for "http://" you'll probably want case-insensitive search:

如果您正在检查“http://”，您可能需要不区分大小写的搜索：

// probably better to check for just http instead of http://
NSRange prefixRange = 
    [temp rangeOfString:@"http" 
                options:(NSAnchoredSearch | NSCaseInsensitiveSearch)];
if (prefixRange.location == NSNotFound)

Although I think the url scheme check is a better answer depending on your circumstances, as URLs can begin with http or https and other prefixes depending on what your use case is.

尽管我认为 url 方案检查是一个更好的答案，具体取决于您的情况，因为 URL 可以以 http 或 https 以及其他前缀开头，具体取决于您的用例是什么。

回答by JuJoDi

First, you should create a new category for NSURL: File > New File > Objective-C Category. You can call the category something along the lines of HTTPURLWithString, make it a category of NSURL, press next and add it to your target. Then in the NSURL+HTTPURLFromString.m implement the following message (and declare the message in your .h)

首先，您应该为 NSURL 创建一个新类别：File > New File > Objective-C Category。您可以按照 HTTPURLWithString 的方式调用该类别，使其成为 NSURL 的类别，然后按下一步并将其添加到您的目标中。然后在 NSURL+HTTPURLFromString.m 中实现以下消息（并在您的 .h 中声明该消息）

@implementation NSURL (HTTPURLFromString)
+(NSURL *)HTTPURLFromString:(NSString *)string
{
    NSString *searchString = @"http";
    NSRange prefixRange = [string rangeOfString:searchString options:(NSCaseInsensitiveSearch | NSAnchoredSearch)];

    if (prefixRange.length == 4) {
        return [NSURL URLWithString:string];
    }
    return [NSURL URLWithString:[NSString stringWithFormat:@"http://%@", string]];

}
@end

To open a link in the WebView is simply

在 WebView 中打开链接很简单

NSString *urlString = @"www.google.com";
NSURL *url = [NSURL HTTPURLFromString:urlString];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[webView.mainFrame loadRequest:request];

回答by d0ping

You can use scheme property for check it out. For example...

您可以使用方案属性进行检查。例如...

if ([yourURL.scheme isEqualToString:@"http"] || [yourURL.scheme isEqualToString:@"https"]) {
    ...
}