问题使用MFMailComposeViewController

Question

我遇到使用MFMailComposeViewController的问题。以下是我尝试在设备上运行的示例代码。我有意添加了5秒的延迟（仅用于模拟下载附件文件的体验），之后应用程序显示“邮件”控制器。在延迟期间，如果我们点击主页按钮，即使应用程序在后台运行并在5秒之前恢复应用程序，则主题字段将为空白，同时消息正文将具有值“消息1”而不是“消息2 “如果我们将应用程序最小化并在5秒后恢复应用程序，主题不会出现，但主体将是”message2“而不是”message 1“。你能帮我理解行为吗？

-(void) func:(MFMailComposeViewController *) mail 
{ 
    [mail setMessageBody:@"message 2" isHTML:NO]; 
    [self presentModalViewController:mail animated:YES];  
} 

- (IBAction)action:(id)sender 
{ 
    MFMailComposeViewController * mail = [[MFMailComposeViewController alloc] init]; 
    [mail setMailComposeDelegate:self]; 
    [mail setMessageBody:@"message 1" isHTML:NO]; 
    [mail setSubject:@"subject 1"]; 

    dispatch_async(dispatch_get_main_queue(), ^{  
     [self performSelector:@selector(func:) withObject:mail afterDelay:5];  
    }); 
} 

感谢

Answer 1

在这里你去！

-(IBAction)email { 
    MFMailComposeViewController *composer = [[MFMailComposeViewController alloc] init]; 
    [composer setMailComposeDelegate:self]; 
    if ([MFMailComposeViewController canSendMail]) { 
     [composer setToRecipients:[NSArray arrayWithObjects:@"", nil]]; 
     [composer setSubject:@""]; 
     [composer setMessageBody:@"" isHTML:NO]; 
     [composer setModalTransitionStyle:UIModalTransitionStyleCrossDissolve]; 
     [self presentModalViewController:composer animated:YES]; 
     [composer release]; 
    } 
    else 
     [composer release]; 
}