应用程序试图在iOS 10中的目标上呈现一个无模式视图控制器？

Question

我在我的应用程序中实现了MFMailComposeViewController，当我点击我的邮件按钮时，我得到了下面的错误。

应用程序试图在目标强大的文本呈现零模态视图控制器

这里是我的代码：

NSString *iOSVersion = [[UIDevice currentDevice] systemVersion]; 
    NSString * version = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"]; 

    NSString * build = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"]; 

    mailComposer = [[MFMailComposeViewController alloc]init]; 
    mailComposer.navigationBar.tintColor = [UIColor blackColor]; 
    [mailComposer.navigationBar setTitleTextAttributes: 
    @{NSForegroundColorAttributeName:[UIColor blackColor]}]; 
    mailComposer.mailComposeDelegate = self; 

    [mailComposer setSubject:@"Co - Contact Us"]; 

    [mailComposer setToRecipients:@[@"[email protected]"]]; 
    NSString *supportText = @"Enter your comment here:\n\n\n\n\n"; 
    supportText = [supportText stringByAppendingString:[NSString stringWithFormat:@"iOS Version: %@\nCorner Version:%@\nBuild:%@\n\n",iOSVersion,version, build]]; 
    [mailComposer setMessageBody:supportText isHTML:NO]; 

    [self presentViewController:mailComposer animated:YES completion:nil]; 

这有什么错我的代码。请帮忙

Answer 1

如果设备没有配置邮件或使用模拟器会导致崩溃或异常。

mailComposer = [[MFMailComposeViewController alloc] init]; 

上面的代码行可能会导致问题。在模拟器初始化方法中可能会返回NULL或nil。

，只需检查canSendMail呈现模式的viewController前：

一样，

NSString *iOSVersion = [[UIDevice currentDevice] systemVersion]; 
    NSString * version = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"]; 

    NSString * build = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"]; 

    mailComposer = [[MFMailComposeViewController alloc]init]; 

    if ([MFMailComposeViewController canSendMail] && mailComposer) { 

     mailComposer.navigationBar.tintColor = [UIColor blackColor]; 
     [mailComposer.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor blackColor]}]; 
     mailComposer.mailComposeDelegate = self; 

     [mailComposer setSubject:@"Corner - Contact Us"]; 

     [mailComposer setToRecipients:@[@"[email protected]"]]; 
     NSString *supportText = @"Enter your comment here:\n\n\n\n\n"; 
     supportText = [supportText stringByAppendingString:[NSString stringWithFormat:@"iOS Version: %@\nCorner Version:%@\nBuild:%@\n\n",iOSVersion,version, build]]; 
     [mailComposer setMessageBody:supportText isHTML:NO]; 

     [self presentViewController:mailComposer animated:YES completion:nil]; 
}