iOS 混合网页开发 问题

_weak typeof(self)weakSelf = self;

JSContext *tContext = [weakSelf.webView valueForKeyPath:@"documentView.webView.mainFrame.javaScriptContext"];

tContext[@"jsredirect"] = ^(){

NSArray *tArgs = [JSContext currentArguments];
JSValue *tJSValue = [tArgs firstObject];

@try
{
NSDictionary *tActionValueDic = [tJSValue toDictionary];

NSLog(@"JSValue:%@", tActionValueDic);

NSString *tUrlStr = tActionValueDic[@"url"];

if ([tUrlStr isEqualToString:@"chartDispose"]) {
[[NSUserDefaults standardUserDefaults] setInteger:0 forKey:@"WebKitCacheModelPreferenceKey"];
[[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"WebKitDiskImageCacheEnabled"];
[[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"WebKitOfflineWebApplicationCacheEnabled"];
[[NSUserDefaults standardUserDefaults] synchronize];
}else{
CGGradeJumpWebViewController *vc = [[CGGradeJumpWebViewController alloc]init];
vc.urlStr = tUrlStr;
NSLog(@"Current Thread:%@",[NSThread currentThread]);
dispatch_async(dispatch_get_main_queue(), ^{
//UI修改
NSLog(@"Current Thread:%@",[NSThread currentThread]);
[weakSelf.navigationController pushViewController:vc animated:YES];
});
}

}
@catch (NSException *exception)
{
NSLog(@"exception:%@", exception);
}
};