func ResetNSURLCredentials() {
    let protectionSpace : NSURLProtectionSpace = NSURLProtectionSpace(host: "xyz.com", port: 0, `protocol`: "http", realm: nil, authenticationMethod: nil)

    for (urlProtectionSpace, users) in NSURLCredentialStorage.sharedCredentialStorage().allCredentials {
        for (userName, credential) in users {

        while(userName == userNameEnumerator.nextObject() as NSEnumerator){
            NSURLCredentialStorage.sharedCredentialStorage().removeCredential(credential, forProtectionSpace: protectionSpace)
        }
    }
}