iphone - MFMailComposeViewController在单独的类中

我试图创建一个可以在多个iPhone项目中使用的“实用程序电子邮件发件人类”。

为此，我创建了MailSender header 和实现。

MailSender.h:

@interface MailSender : NSObject<MFMailComposeViewControllerDelegate>

- (id) initWithParent:(UIViewController*) mainController;

- (void) invokeMailSender:(NSString*) to:(NSString*) subject:(NSString*) failureTitle:(NSString*) failureMessage:(NSString*) failureCancel;

@end

MailSender.m:

#import "MailSender.h"

@implementation MailSender

MFMailComposeViewController* mailer;
UIViewController* mailParentController;

- (id) initWithParent:(UIViewController*) mainController
{
    if( self = [super init])
    {
      mailParentController = mainController;
    }
    return self;
}

- (void) invokeMailSender:(NSString*) to:(NSString*) subject:(NSString*) failureTitle:(NSString*) failureMessage:(NSString*) failureCancel;

{
    if([MFMailComposeViewController canSendMail])
    {
        mailer = [[MFMailComposeViewController alloc] init];

        mailer.mailComposeDelegate = self;

        [mailer setSubject:subject];

        NSArray *toRecipients = [NSArray arrayWithObjects:to, nil];

        [mailer setToRecipients:toRecipients];
       [mailParentController presentModalViewController:mailer animated:YES];
    }
    else
    {
        UIAlertView* alert = [[UIAlertView alloc] initWithTitle:failureTitle message:failureMessage
                                                       delegate:nil cancelButtonTitle:failureCancel otherButtonTitles: nil];

        [alert show];
    }
}

-(void)mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error
{
    // Do nothing
    [mailParentController dismissModalViewControllerAnimated:YES];
    mailer = nil;
}



@end

我使用以下说明从 View Controller (通过按钮按下操作)中调用了该类:

@implementation InfoViewController

MailSender *sender;

- (IBAction)openMail:(id)sender
{
    sender = [[MailSender alloc] initWithParent:self];
    [sender invokeMailSender:@"[email protected]" :@"123" :@"123" :@"123" :@"123"];
}

....
@end

运行代码时，我可以正确显示电子邮件 View 。但是，这之后将导致崩溃。
请注意，当直接从我的UIViewController使用MFMailComposeViewController时，我并没有崩溃(并且将View Controller分配为委托(delegate))，

有任何想法吗？
抱歉，我还是Objective C的新手:)

最佳答案

您需要保留发件人MailSender实例。调用调用消息后，它将被释放。

您可以通过声明一个名为property的sender来做到这一点。例如。

@property (strong, nonatomic) MailSender *sender;
...
@synthesize sender = _sender;
...
self.sender = [[MailSender alloc] initWithParent:self];
[self.sender invokeMailSender:@"[email protected]" :@"123" :@"123" :@"123" :@"123"];

顺便说一句，您的方法声明有点有趣。您应该命名参数。例如。

- (void)invokeMailSender:(NSString *)sender
                      to:(NSString *)to
                 subject:(NSString *)subject
            failureTitle:(NSString *)failureTitle
          failureMessage:(NSString *)failureMessage
failureCancelButtonTitle:(NSString *)failureCancelButtonTitle