iPhone:电子邮件API MFMailComposeViewController在设备上崩溃

Question

当我尝试在设备上使用MFMailComposeViewController时,我得到以下给出的崩溃日志.

当我尝试在模拟器上运行它时,它会打开模态视图.

这是我正在使用的代码:

stringHTML并且html是HTML字符串.

stringHTML是NSString html类型,类型为NSMutableString.

MFMailComposeViewController *mailController = [[MFMailComposeViewController alloc] init];
    mailController.mailComposeDelegate = self;
[mailController setSubject:@"Email"];
NSLog(@"%@",html);
NSString *stringHTML=html;
NSLog(@"%@",stringHTML);
[mailController setMessageBody:stringHTML isHTML:YES];
[self presentModalViewController:mailController animated:YES];
[mailController release];

可能有什么不对？

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present a nil modal view controller on target <QuizReportsView: 0x411af0>.'
*** Call stack at first throw:
(
0   CoreFoundation                      0x3737364f __exceptionPreprocess + 114
1   libobjc.A.dylib                     0x33a30c5d objc_exception_throw + 24
2   UIKit                               0x31350fcf -[UIViewController presentModalViewController:withTransition:] + 546
3   UIKit                               0x31350cd7 -[UIViewController presentModalViewController:animated:] + 58
4   Vocab                               0x0007d1bf -[QuizReportsView actionSheet:clickedButtonAtIndex:] + 270
5   UIKit                               0x313c603d -[UIActionSheet(Private) _buttonClicked:] + 192
6   CoreFoundation                      0x372e3571 -[NSObject(NSObject) performSelector:withObject:withObject:] + 24
7   UIKit                               0x312c3ec9 -[UIApplication sendAction:to:from:forEvent:] + 84
8   UIKit                               0x312c3e69 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 32
9   UIKit                               0x312c3e3b -[UIControl sendAction:to:forEvent:] + 38
10  UIKit                               0x312c3b8d -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 356
11  UIKit                               0x312c4423 -[UIControl touchesEnded:withEvent:] + 342
12  UIKit                               0x312c2bf5 -[UIWindow _sendTouchesForEvent:] + 368
13  UIKit                               0x312c256f -[UIWindow sendEvent:] + 262
14  UIKit                               0x312ab313 -[UIApplication sendEvent:] + 298
15  UIKit                               0x312aac53 _UIApplicationHandleEvent + 5090
16  GraphicsServices                    0x31c36e77 PurpleEventCallback + 666
17  CoreFoundation                      0x3734aa97 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 26
18  CoreFoundation                      0x3734c83f __CFRunLoopDoSource1 + 166
19  CoreFoundation                      0x3734d60d __CFRunLoopRun + 520
20  CoreFoundation                      0x372ddec3 CFRunLoopRunSpecific + 230
21  CoreFoundation                      0x372dddcb CFRunLoopRunInMode + 58
22  GraphicsServices                    0x31c3641f GSEventRunModal + 114
23  GraphicsServices                    0x31c364cb GSEventRun + 62
24  UIKit                               0x312d5d69 -[UIApplication _run] + 404
25  UIKit                               0x312d3807 UIApplicationMain + 670
26  Vocab                               0x00002223 main + 82
27  Vocab                               0x000021cc start + 40
)
terminate called after throwing an instance of 'NSException'

Answer 1

试试这个

//check if device is configured to send mails
if([MFMailComposeViewController canSendMail]){
  MFMailComposeViewController *mailController = [[MFMailComposeViewController alloc] init];
  if(mailController)
  {
    mailController.mailComposeDelegate = self;
   [mailController setSubject:@"Email"];
    NSLog(@"%@",html);
    NSString *stringHTML=html;
    NSLog(@"%@",stringHTML);
    [mailController setMessageBody:stringHTML isHTML:YES];
    [self presentModalViewController:mailController animated:YES];
    [mailController release];
  }
}

Answer 2

从错误很明显,您正在呈现nil 模态视图控制器.

检查MFMailComposeViewController是否正确构造它的对象 .

和Aslo MFMailComposeViewController在iOS 3.0及更高版本中可用.

尝试使用以下代码

MFMailComposeViewController *mailController = [[MFMailComposeViewController alloc] init];
if(mailController)
{
    mailController.mailComposeDelegate = self;
   [mailController setSubject:@"Email"];
    NSLog(@"%@",html);
    NSString *stringHTML=html;
    NSLog(@"%@",stringHTML);
    [mailController setMessageBody:stringHTML isHTML:YES];
    [self presentModalViewController:mailController animated:YES];
    [mailController release];
}

有关下面的更多信息

应用程序试图提出一个零模态视图...

模态视图控制器的问题