iOS修改UserAgent

由于特殊需求，有时候需要给UserAgent添加相应的内容，一般都是尾部添加：

-(void)registUserAgent{
    UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectZero];
    NSString *oldAgent = [webView stringByEvaluatingJavaScriptFromString:@"navigator.userAgent"];
    NSLog(@"old agent :%@", oldAgent);
    NSString *newAgent;
    if (![oldAgent hasSuffix:@"yonglian"]) {
        newAgent = [oldAgent stringByAppendingString:@" yonglian"];
    }else{
        newAgent = oldAgent;
    }
    //add my info to the new agent
    NSLog(@"new agent :%@", newAgent);
    
    //regist the new agent
    NSDictionary *dictionnary = [[NSDictionary alloc] initWithObjectsAndKeys:newAgent, @"UserAgent", nil];
    [[NSUserDefaults standardUserDefaults] registerDefaults:dictionnary];
    [[NSUserDefaults standardUserDefaults] synchronize];
}
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添加最好是在程序启动的时候：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
    
}
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亲测，其他方式都不管用，只能在一开始就添加。