UIWebView iOS5 changing user-agent - objective-c

Question

How can I change the user-agent of UIWebView in iOS 5?
What I have done so far:
Using the delegate call back, intercept the NSURLRequest, create a new url request and set it's user-agent as whatever I want, then download the data and reload the UIWebView with "loadData:MIMEType:....".
Problem:
This causes infinite recursion, where I load the data, which calls the delegate back, which intern calls the delegate....
Here's the delegate method:
- (BOOL)webView:(UIWebView *)aWebView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
dispatch_async(kBgQueue, ^{
NSURLResponse *response = nil;
NSMutableURLRequest *newRequest = [NSMutableURLRequest requestWithURL:[request URL]];
NSDictionary *headers = [NSDictionary dictionaryWithObject:
#"custom_test_agent" forKey:#"User-Agent"];
[newRequest setAllHTTPHeaderFields:headers];
[self setCurrentReqest:newRequest];
NSData *data = [NSURLConnection sendSynchronousRequest:newRequest
returningResponse:&response
error:nil];
dispatch_sync(dispatch_get_main_queue(), ^{
[webView loadData:data
MIMEType:[response MIMEType]
textEncodingName:[response textEncodingName]
baseURL:[request URL]];
});
});
return YES;
}

Answer 1

Change the "UserAgent" default value by running this code once when your app starts:
NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:#"Your user agent", #"UserAgent", nil];
[[NSUserDefaults standardUserDefaults] registerDefaults:dictionary];
EDIT: I have used this with great success, but want to add additional details. To get a user agent, you can enable the "Developer" menu, set the user agent, and then connect to this site to get it printed out for you: WhatsMyAgent. Likewise you can connect using any kind of mobile device, and get it that way too. BTW this is still working just fine in iOS7+

Answer 2

In Swift use this to set UserAgent,
func setUserAgent(){
var userAgent = NSDictionary(objectsAndKeys: "YourUserAgentName","UserAgent")
NSUserDefaults.standardUserDefaults().registerDefaults(userAgent as [NSObject : AnyObject])
}
Use this to test,
println(WebView.stringByEvaluatingJavaScriptFromString("navigator.userAgent"));

Answer 3

When you send message [aWebView loadData:MIMEType:textEncodingName:baseURL:]
then aWebView shouldStartLoadWithRequest: will be called again, and then again - that is why you get an infinite recursion
You should restrict calling of your dispatch_async() block, for example by using some conventional URL:
- (BOOL)webView:(UIWebView *)aWebView shouldStartLoadWithRequest:(NSURLRequest *)request
navigationType:(UIWebViewNavigationType)navigationType {
if ([[[request URL] absoluteString] isEqualToString:#"http://yourdomain.com/?local=true"]) {
return YES;
}
...
dispatch_async(...
[aWebView loadData:data
MIMEType:[response MIMEType]
textEncodingName:[response textEncodingName]
baseURL:[NSURL URLWithString:#"http://yourdomain.com/?local=true"]];
);
return NO;
}