将 MFMailComposeViewController 推送到导航堆栈上？不以模态方式呈现
我有一个表格视图，在其中一个单元格中，它显示“联系人”。选择此单元格后，我想推入 MFMailComposeViewController。
我似乎只能以模态方式呈现这个 MFMailComposeViewController 。这里有什么问题呢？
谢谢！
相关代码片段：
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
MFMailComposeViewController *controller = [[MFMailComposeViewController alloc] init];
//*works*//[self.navigationController presentModalViewController:controller animated:YES];
//*broken*//[self.navigationController pushViewController:controller animated:YES];
}
我得到的错误是：“ * 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“不支持推送导航控制器” *第一次抛出调用堆栈：“
所以看起来我已经有了一个navigationController，并且由于MFMailComposeViewController是UINavigationController的子类，所以我将一个navController推到另一个navController上？
我希望我的UI保持一致，所以我想将 MFMailComposeViewController 推送到导航堆栈上，而不是以模态方式呈现它。
I have a table view, and in one of the cells, it says "contact". Upon selecting this cell, I'd like to push in a MFMailComposeViewController.
I can only seem to present this MFMailComposeViewController modally. What is the problem here?
Thanks!
Relevant code frag:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
MFMailComposeViewController *controller = [[MFMailComposeViewController alloc] init];
//*works*//[self.navigationController presentModalViewController:controller animated:YES];
//*broken*//[self.navigationController pushViewController:controller animated:YES];
}
The error that I get is: " * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Pushing a navigation controller is not supported'
* Call stack at first throw:"
So it looks like I have a navigationController already, and since MFMailComposeViewController is a subclass of UINavigationController, I'm pushing a navController onto another navController?
I want my UI to be consistent, so I want to push a MFMailComposeViewController onto the nav stack rather than present it modally.
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这是因为
MFMailComposeViewController不是UIViewController的子类，而是UINavigationController的子类。当您尝试将UINavigationController或UINavigationController的子类推送到现有堆栈时，UINavigationController会引发异常。允许以模态方式呈现UINavigationController。This is because
MFMailComposeViewControllerisn't a subclass ofUIViewControllerbut ofUINavigationController.UINavigationControllerthrows an exception when you're attempting to push aUINavigationControlleror subclass ofUINavigationControlleronto an existing stack. Presenting aUINavigationControllermodally is permitted.根据苹果文档
因此您尝试做的事情应该在这两种情况下都有效。你看过日志吗？
我敢打赌你的navigationController是nil，因为这通常发生在你使用普通的UIViewController（没有嵌入
UINavigationController中，但如果你实际上将你的模态视图呈现到navigationController上，它可能不会零。According to Apple documentation
So what you are trying to do is supposed to work in both cases. Did you have a look at the logs ?
I would have bet your navigationController is nil, because this typically happens when you are using a plain UIViewController (not embedded in a
UINavigationController, but it you actually present your modal view onto the navigationController, it may not be nil.