一个关于iphone应用邮件功能的问题

邮件功能也许没有太多需要说的，这里要说的是有关邮件功能涉及到的一些细节问题。先看一段代码：

- (void)LaunchMailComposer:(UIButton *)sender

{

NSArray *Array = [ImageArray objectAtIndex:sender.tag-1];

NSString *URL = [Array objectAtIndex:1];

MFMailComposeViewController *Composer = [[MFMailComposeViewController alloc] init];

//Composer = [Composer init];

NSLog(@"composer description:%@",[Composer description]);

Composer.mailComposeDelegate = self;

//NSArray *toRecipients = nil;

// NSArray *ccRecipients = nil;

// NSArray *bccRecipients = nil;

// [Composer setToRecipients:toRecipients];

// [Composer setCcRecipients:ccRecipients];

// [Composer setBccRecipients:bccRecipients];

NSString *Body = [NSString stringWithFormat:@"<style type='text/css'><!-- body{background-image:url(%@)} --></style>", URL];

//NSString *Body = @"<style type='text/css'><!-- body{background-image:url(http://www.4oa.com/Article/UploadPic/2009-4/2009429102347901.jpg)} --></style>";

[Composer setMessageBody:Body isHTML:YES];

if (nil == Composer) {

return;

}

[self presentModalViewController:Composer animated:YES];

[Composer release];

}

上面的代码本身并没有什么问题，在通常来说也不会有什么问题，但是做一个有趣的操作，把所有的默认设置好的邮箱都删除，奇怪的事情出现了，如果仅仅是上面的方式来设置邮件功能回导致程序崩溃。认真调试，怎么会初始化失败呢？原来，忘记了是否能发送邮件。那么我们在看如下的代码：

- (void)LaunchMailComposer:(UIButton *)sender

{

NSArray *Array = [ImageArray objectAtIndex:sender.tag-1];

NSString *URL = [Array objectAtIndex:1];

if (![MFMailComposeViewController canSendMail]) {

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Warning" message:@"Please set your mail address!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

return;

}

MFMailComposeViewController *Composer = [[MFMailComposeViewController alloc] init];

//Composer = [Composer init];

NSLog(@"composer description:%@",[Composer description]);

Composer.mailComposeDelegate = self;

//NSArray *toRecipients = nil;

// NSArray *ccRecipients = nil;

// NSArray *bccRecipients = nil;

// [Composer setToRecipients:toRecipients];

// [Composer setCcRecipients:ccRecipients];

// [Composer setBccRecipients:bccRecipients];

NSString *Body = [NSString stringWithFormat:@"<style type='text/css'><!-- body{background-image:url(%@)} --></style>", URL];

//NSString *Body = @"<style type='text/css'><!-- body{background-image:url(http://www.4oa.com/Article/UploadPic/2009-4/2009429102347901.jpg)} --></style>";

[Composer setMessageBody:Body isHTML:YES];

if (nil == Composer) {

return;

}

[self presentModalViewController:Composer animated:YES];

[Composer release];

}

其实就只是多了一个判断条件这样就好了。可是我们如果想要在没有设置邮件帐号的情况下进入到设置页面呢？

那么我们可以用如下方式：

-(IBAction)emailBTN:(id)sender

{

Class mailClass = (NSClassFromString(@"MFMailComposeViewController"));

if (mailClass != Nil)

{

// We must always check whether the current device is configured for sending emails

if ([mailClass canSendMail])

{

[self displayComposerSheet];

}

else

{

[self launchMailAppOnDevice];

}

}

else

{

[self launchMailAppOnDevice];

}

}

#pragma mark -

#pragma mark Compose Mail

-(void)displayComposerSheet

{

MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init];

picker.mailComposeDelegate = self;

[picker setSubject:[imageNameArray objectAtIndex:picNumber]];//@"Hello from California!"];

// Set up recipients

NSArray *toRecipients = [NSArray arrayWithObject:@"fengxijun51020@hotmail.com"];

NSArray *ccRecipients = nil;//[NSArray arrayWithObjects:@"second@example.com", @"third@example.com", nil];

NSArray *bccRecipients = nil;//[NSArray arrayWithObject:@"fourth@example.com"];

[picker setToRecipients:toRecipients];

[picker setCcRecipients:ccRecipients];

[picker setBccRecipients:bccRecipients];

// Attach an image to the email

NSString *path = [[NSBundle mainBundle] pathForResource:[imageNameArray objectAtIndex:picNumber] ofType:@"jpg"];

NSData *myData = [NSData dataWithContentsOfFile:path];

[picker addAttachmentData:myData mimeType:@"image/jpg" fileName:[imageNameArray objectAtIndex:picNumber]];

// Fill out the email body text

NSString *emailBody = nil;//[imageNameArray objectAtIndex:picNumber];

[picker setMessageBody:emailBody isHTML:NO];

[self presentModalViewController:picker animated:YES];

[picker release];

}

// Dismisses the email composition interface when users tap Cancel or Send. Proceeds to update the message field with the result of the operation.

- (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error

{

// Notifies users about errors associated with the interface

switch (result)

{

case MFMailComposeResultCancelled:

[self dismissModalViewControllerAnimated:YES];

break;

case MFMailComposeResultSaved:

[self sendResult:@"/n/nE-mail saved!"];

break;

case MFMailComposeResultSent:

[self sendResult:@"/n/nSent succeed!"];

break;

case MFMailComposeResultFailed:

[self sendResult:@"send Failed!"];

break;

}

}

-(void)sendResult:(NSString *)string

{

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:string delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];

[alert show];

[self performSelector:@selector(delayDismissModalView:) withObject:alert afterDelay:1];

}

-(void)delayDismissModalView:(UIAlertView *)alert

{

[alert dismissWithClickedButtonIndex:0 animated:YES];

[self dismissModalViewControllerAnimated:YES];

[alert release];

}

#pragma mark -

#pragma mark Workaround

// Launches the Mail application on the device.

-(void)launchMailAppOnDevice

{

NSString *recipients = @"mailto:first@example.com?cc=second@example.com,third@example.com&subject=Hello from California!";

NSString *body = @"&body=It is raining in sunny California!";

NSString *email = [NSString stringWithFormat:@"%@%@", recipients, body];

email = [email stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:email]];

}

这样邮件功能就做好了。

小提示：在写代码是一定要逻辑严谨，否则出现了问题是很难调试的，特别是与人合作进行开发的过程中这点尤其重要。