MFMailComposeViewController - iPad

Question

我已经设置了一个MFMailComposeViewController，它可以在iPhone上正常工作，但在iPad上崩溃，说：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present a nil modal view controller on target...

那为什么会创建一个零模态视图呢？

    MFMailComposeViewController *message = [[MFMailComposeViewController alloc] init];
    [message setMessageBody:@"My message here"  isHTML:NO];
    [message setToRecipients:[NSArray arrayWithObject:@"my@domain.com"]];
    [message setSubject:@"Request Info"];
    message.mailComposeDelegate = self;
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
        message.modalPresentationStyle = UIModalPresentationFormSheet;
    [self presentModalViewController:message animated:YES];
    [message release];

有什么想法吗？

Answer 1

MFMailComposeViewController之类的Loos由于某种原因未创建，因此具有nil值。在呈现之前检查它是否为零（虽然这种解决方法不能回答这里出了什么问题......）。

您还应该检查邮件编辑器是否可以在尝试使用+canSendMail方法创建和发送邮件之前发送邮件（例如，如果设备上没有设置邮件帐户，则会返回NO）：

 if ([MFMailComposeViewController canSendMail]){
    // Create and show composer
 }
 else{
   // Show some error message here
 }

Answer 2

在创建canSendMail对象之前，您必须放置检查MFMailComposerViewController，请参阅MFMailComposeViewController.h类的以下注释：

/*!
@method     canSendMail
@abstract   Returns <tt>YES</tt> if the user has set up the device for sending email.
@discussion The client may continue to set the recipients and content if the return value was <tt>YES</tt>.  If <tt>NO</tt>
            was the result, the client has a couple options.  It may choose to simply notify the user of the inability to
            send mail, or it may issue a "mailto" URL via <tt>-[UIApplication openURL:]</tt>.
*/

+ (BOOL)canSendMail __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);

在您的设备设置为发送邮件之前，您的对象不会被初始化。

Answer 3

if ([MFMailComposeViewController   canSendMail]){
    //execute  your    code 
else{
    UIAlertView *anAlert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"No mail account setup on device" delegate:self cancelButtonTitle:nil otherButtonTitles:nil];     
    [anAlert addButtonWithTitle:@"OK"];
    [anAlert show];
}

如果您收到提醒，请在手机上配置您的邮件帐户。

Answer 4

这是因为您的iOS默认邮件应用程序尚未配置任何邮件ID。所以使用你的任何邮件ID进行配置并尝试。

像这样

if ([MFMailComposeViewController canSendMail]){
    MFMailComposeViewController *controller = [[MFMailComposeViewController alloc] init];
    controller.mailComposeDelegate = self;
    [controller setToRecipients:[NSArray arrayWithObject:eMail]];
    [self presentViewController:controller animated:YES completion:nil];
}
else{
    UIAlertView *anAlert = [[UIAlertView alloc] initWithTitle:@"error" message:@"No mail account setup on device" delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
    [anAlert addButtonWithTitle:@"Cancel"];
    [anAlert show];
}

希望对你有所帮助。

Answer 5

您的测试设备上没有设置邮件帐户。

if ([MFMailComposeViewController canSendMail]){

//execute your code else{
UIAlertView *anAlert = [[UIAlertView alloc] initWithTitle:@"error" message:@"No mail account setup on device" delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
    [anAlert addButtonWithTitle:@"Cancel"];
    [anAlert show];
}