應用程序試圖在iOS 10中的目標上呈現一個無模式視圖控制器？

Question

我在我的應用程序中實現了MFMailComposeViewController，當我點擊我的郵件按鈕時，我得到了下面的錯誤。

應用程序試圖在目標強大的文本呈現零模態視圖控制器

這裏是我的代碼：

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:@[@"contact@co.org"]]; 
    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]; 

這有什麼錯我的代碼。請幫忙

Answer 1

如果設備沒有配置郵件或使用模擬器會導致崩潰或異常。

mailComposer = [[MFMailComposeViewController alloc] init]; 

上面的代碼行可能會導致問題。在模擬器初始化方法中可能會返回NULL或nil。

，只需檢查canSendMail呈現模式的viewController前：

一樣，

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:@[@"contact@corner.org"]]; 
     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]; 
}