Question: I want to be able to send some extra headers with my UIWebView `loadRequest` method.

I have tried:

```
NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.reliply.org/tools/requestheaders.php"]];
[req addValue:@"hello" forHTTPHeaderField:@"aHeader"];

[self.theWebView loadRequest:req];

```

I have also tried subclassing the `UIWebView` and intercepting the `- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType` method.

In that method I had a block of code which looked like this:

```
NSMutableURLRequest *newRequest = [request mutableCopy];
for(NSString *key in [customHeaders allKeys]) {
    [newRequest setValue:[customHeaders valueForKey:key] forHTTPHeaderField:key];
}
[self loadRequest:newRequest];

```

But for some unknown reason it was causing the web view to not load anything (blank frame) and the error message `NSURLErrorCancelled (-999)` comes up (all known fixes don't fix it for me).

So I am at a loss as to what to do. How can I send a custom header along with a `UIWebView` request?

Many thanks!

Answer: 
I found that this was the way to add headers to my UIWebView request - override this delegate method:

```
- (BOOL) webView:(UIWebView*)webView shouldStartLoadWithRequest:(NSURLRequest*)request navigationType:(UIWebViewNavigationType) navigationType

```

With this code:

```
BOOL headerIsPresent = [[request allHTTPHeaderFields] objectForKey:@"my custom header"]!=nil;

if(headerIsPresent) return YES;

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_async(dispatch_get_main_queue(), ^{
        NSURL *url = [request URL];
        NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];

        // set the new headers
        for(NSString *key in [self.customHeaders allKeys]){
            [request addValue:[self.customHeaders objectForKey:key] forHTTPHeaderField:key];
        }

        // reload the request
        [self loadRequest:request];
    });
});
return NO;

```
I find another way, Can use `NSURLProtocol` .

```
-(BOOL)webView:(IMYVKWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
    NSMutableDictionary* mapObject = [NSMutableDictionary dictionary];
    mapObject[@"headers"] = request.allHTTPHeaderFields;
    mapObject[@"navigationType"] = @(navigationType);
    [webViewRequestMap setObject:mapObject forKey:request.URL.absoluteString];
    return YES;
}

```

`webViewRequestMap` is Static NSMutableDictionary\*

in Your Custom NSURLProtocol code:

```
    @interface IMYCustomURLProtocol : NSURLProtocol
@end
@implementation IMYCustomURLProtocol 
+(void)load
{
     [NSURLProtocol registerClass:self];
}
+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
    NSString* urlString = request.URL.absoluteString;
    NSDictionary* dictionary = webViewReuqestMap[urlString];
    if (dictionary)
    {
        [webViewRequestMap removeObjectForKey:urlString];
        if ([request isKindOfClass:[NSMutableURLRequest class]]) {
           [(id)request setValue:@"HAHA" forHTTPHeaderField:@"MeiYou Co.,Ltd"];
        }
    }
    return NO;
}
@end

```