iOS自定义返回按钮(不影响返回手势)

 此方法可以自定义返回按钮，且不影响返回手势。

新方法： self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]
initWithImage:img
style:UIBarButtonItemStylePlain
target:self
action:@selector(onBack:)];
self.navigationController.interactivePopGestureRecognizer.delegate = (id<UIGestureRecognizerDelegate>)self;

老方法：

UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:self action:nil];
self.navigationController.navigationBar.topItem.backBarButtonItem = backButton;