发邮件

1.openURL
使用openURL调用系统邮箱客户端是我们在IOS3.0以下实现发邮件功能的主要手段。我们可以通过设置url里的相关参数来指定邮件的内容，不过其缺点很明显，这样的过程会导致程序暂时退出。下面是使用openURL来发邮件的一个小例子：

#pragma mark - 使用系统邮件客户端发送邮件
-(void)launchMailApp
{
NSMutableString *mailUrl = [[[NSMutableString alloc]init]autorelease];
//添加收件人
NSArray *toRecipients = [NSArray arrayWithObject: @"first@example.com"];
[mailUrl appendFormat:@"mailto:%@", [toRecipients componentsJoinedByString:@","]];
//添加抄送
NSArray *ccRecipients = [NSArray arrayWithObjects:@"second@example.com", @"third@example.com", nil];
[mailUrl appendFormat:@"?cc=%@", [ccRecipients componentsJoinedByString:@","]];
//添加密送
NSArray *bccRecipients = [NSArray arrayWithObjects:@"fourth@example.com", nil];
[mailUrl appendFormat:@"&bcc=%@", [bccRecipients componentsJoinedByString:@","]];
//添加主题
[mailUrl appendString:@"&subject=my email"];
//添加邮件内容
[mailUrl appendString:@"&body=<b>email</b> body!"];
NSString* email = [mailUrl stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding];
[[UIApplication sharedApplication] openURL: [NSURL URLWithString:email]];
}

2.MFMailComposeViewController
MFMailComposeViewController是在IOS3.0新增的一个接口，它在MessageUI.framework中。通过调用MFMailComposeViewController，可以把邮件发送窗口集成到我们的应用里，发送邮件就不需要退出程序了。MFMailComposeViewController的使用方法：

1.项目中引入MessageUI.framework；
2.在使用的文件中导入MFMailComposeViewController.h头文件；
3.实现MFMailComposeViewControllerDelegate，处理邮件发送事件；
4.调出邮件发送窗口前先使用MFMailComposeViewController里的“+ (BOOL)canSendMail”方法检查用户是否设置了邮件账户；
5.初始化MFMailComposeViewController，构造邮件体

//
//  ViewController.h
//  MailDemo
//
//  Created by LUOYL on 12-4-4.
//  Copyright (c) 2012年 http://luoyl.info. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <MessageUI/MFMailComposeViewController.h>

@interface ViewController : UIViewController<MFMailComposeViewControllerDelegate>

@end

#pragma mark - 在应用内发送邮件
//激活邮件功能
- (void)sendMailInApp
{
Class mailClass = (NSClassFromString(@"MFMailComposeViewController"));
if (!mailClass) {
[self alertWithMessage:@"当前系统版本不支持应用内发送邮件功能，您可以使用mailto方法代替"];
return;
}
if (![mailClass canSendMail]) {
[self alertWithMessage:@"用户没有设置邮件账户"];
return;
}
[self displayMailPicker];
}

//调出邮件发送窗口
- (void)displayMailPicker
{
MFMailComposeViewController *mailPicker = [[MFMailComposeViewController alloc] init];
mailPicker.mailComposeDelegate = self;

//设置主题
[mailPicker setSubject: @"eMail主题"];
//添加收件人
NSArray *toRecipients = [NSArray arrayWithObject: @"first@example.com"];
[mailPicker setToRecipients: toRecipients];
//添加抄送
NSArray *ccRecipients = [NSArray arrayWithObjects:@"second@example.com", @"third@example.com", nil];
[mailPicker setCcRecipients:ccRecipients];
//添加密送
NSArray *bccRecipients = [NSArray arrayWithObjects:@"fourth@example.com", nil];
[mailPicker setBccRecipients:bccRecipients];

// 添加一张图片
UIImage *addPic = [UIImage imageNamed: @"Icon@2x.png"];
NSData *imageData = UIImagePNGRepresentation(addPic);            // png
//关于mimeType：http://www.iana.org/assignments/media-types/index.html
[mailPicker addAttachmentData: imageData mimeType: @"" fileName: @"Icon.png"];

//添加一个pdf附件
NSString *file = [self fullBundlePathFromRelativePath:@"高质量C++编程指南.pdf"];
NSData *pdf = [NSData dataWithContentsOfFile:file];
[mailPicker addAttachmentData: pdf mimeType: @"" fileName: @"高质量C++编程指南.pdf"];

NSString *emailBody = @"<font color='red'>eMail</font> 正文";
[mailPicker setMessageBody:emailBody isHTML:YES];
[self presentModalViewController: mailPicker animated:YES];
[mailPicker release];
}

#pragma mark - 实现 MFMailComposeViewControllerDelegate
- (void)mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error
{
//关闭邮件发送窗口
[self dismissModalViewControllerAnimated:YES];
NSString *msg;
switch (result) {
case MFMailComposeResultCancelled:
msg = @"用户取消编辑邮件";
break;
case MFMailComposeResultSaved:
msg = @"用户成功保存邮件";
break;
case MFMailComposeResultSent:
msg = @"用户点击发送，将邮件放到队列中，还没发送";
break;
case MFMailComposeResultFailed:
msg = @"用户试图保存或者发送邮件失败";
break;
default:
msg = @"";
break;
}
[self alertWithMessage:msg];
}