发送Email的两种方法（IOS原生）

IOS系统框架提供的两种发送Email的方法：openURL 和 MFMailComposeViewController。借助这两个方法，我们可以轻松的在应用里加入如用户反馈这类需要发送邮件的功能。

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]];     
}  

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

#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];   
}