我在将照片库中的图像附加到电子邮件时遇到了一些问题。
基本上,我的应用程序的一项功能允许用户拍照。当他们拍摄照片时,我会在 Core Data 中记录对图像的 URL 引用。我知道您必须通过ALAssetRepresentation
到达图像。当用户想要查看他们拍摄的图像时,我在我的应用程序中启动并运行了它。
我现在正试图允许用户将所有为事件拍摄的照片附加到电子邮件中。在执行此操作时,我遍历存储 URL 引用的核心数据实体,调用返回 UIImage
的方法。来自 ALAssetsLibrary
然后使用 NSData
附加它/UIImageJPEGRepresentation
和 MFMailComposeViewController
/addAttachmentData
方法。
问题是:当电子邮件呈现给用户时,有代表图像的蓝色小方 block ,并且没有附加图像。
这是代码:
- (void)sendReportReport
{
if ([MFMailComposeViewController canSendMail])
{
MFMailComposeViewController *mailer = [[MFMailComposeViewController alloc] init];
mailer.mailComposeDelegate = self;
[mailer setSubject:@"Log: Report"];
NSArray *toRecipients = [NSArray arrayWithObjects:@"someone@someco.com", nil];
[mailer setToRecipients:toRecipients];
NSError *error;
NSFetchRequest *fetchPhotos = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:@"Photo" inManagedObjectContext:__managedObjectContext];
[fetchPhotos setEntity:entity];
NSArray *fetchedPhotos = [__managedObjectContext executeFetchRequest:fetchPhotos error:&error];
int counter;
for (NSManagedObject *managedObject in fetchedPhotos ) {
Photo *photo = (Photo *)managedObject;
// UIImage *myImage = [UIImage imageNamed:[NSString stringWithFormat:@"%@.png", counter++]];
NSData *imageData = UIImageJPEGRepresentation([self getImage:photo.referenceURL], 0.5);
// NSData *imageData = UIImagePNGRepresentation([self getImage:photo.referenceURL]);
// [mailer addAttachmentData:imageData mimeType:@"image/jpeg" fileName:[NSString stringWithFormat:@"%i", counter]];
[mailer addAttachmentData:imageData mimeType:@"image/jpeg" fileName:[NSString stringWithFormat:@"a.jpg"]];
counter++;
}
NSString *emailBody = [self getEmailBody];
[mailer setMessageBody:emailBody isHTML:NO];
[self presentModalViewController:mailer animated:YES];
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Failure"
message:@"Your device doesn't support the composer sheet"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
}
}
以及返回
UIImage
的方法:#pragma mark - Get Photo from Asset Library
+ (ALAssetsLibrary *)defaultAssetsLibrary {
static dispatch_once_t pred = 0;
static ALAssetsLibrary *library = nil;
dispatch_once(&pred, ^{
library = [[ALAssetsLibrary alloc] init];
});
return library;
}
- (UIImage *)getImage:(NSString *)URLReference
{
__block UIImage *xPhoto = nil;
ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
{
UIImage *xImage;
// get the image
ALAssetRepresentation *rep = [myasset defaultRepresentation];
CGImageRef iref = [rep fullScreenImage];
if (iref) {
xImage = [UIImage imageWithCGImage:iref];
}
xPhoto = xImage;
};
ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror)
{
NSLog(@"Error fetching photo: %@",[myerror localizedDescription]);
};
NSURL *asseturl = [NSURL URLWithString:URLReference];
// create library and set callbacks
ALAssetsLibrary *al = [DetailsViewController defaultAssetsLibrary];
[al assetForURL:asseturl
resultBlock:resultblock
failureBlock:failureblock];
return xPhoto;
}
注意:上面的代码确实运行,它只是不附加图像。另外,请注意,只要我将它们设置为
UIImageView
,我就可以在我的应用程序中成功附加图库中的图像。 .Image 已经(基本上,我从 UIImageView
获取指向图像的指针并将其传递给 addAttachmentData
方法。)这只是当我尝试遍历核心数据并附加而不首先将图像设置为UIImageView
我有麻烦了。任何提示将非常感谢!
谢谢!
杰森
最佳答案
哦,现在我明白了.. sry。您正在使用异步 block 从 Assets 库中获取图像。但是在开始该操作后,您将返回 xImage
.但异步操作将在稍后完成。所以你返回零。
你需要像这样改变你的架构师:
在您的 .h 文件中,您需要两个新成员:
NSMutableArray* mArrayForImages;
NSInteger mUnfinishedRequests;
在你的 .m 文件中这样做:
- (void)sendReportReport
{
// save image count
mUnfinishedRequests = [fetchedPhotos count];
// get fetchedPhotos
[...]
// first step: load images
for (NSManagedObject *managedObject in fetchedPhotos )
{
[self loadImage:photo.referenceURL];
}
}
将您的 getImage 方法更改为 loadImage:
- (void)loadImage:(NSString *)URLReference
{
NSURL *asseturl = [NSURL URLWithString:URLReference];
ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
{
// get the image
ALAssetRepresentation *rep = [myasset defaultRepresentation];
CGImageRef iref = [rep fullScreenImage];
if (iref) {
[mArrayForImages addObject: [UIImage imageWithCGImage:iref]];
} else {
// handle error
}
[self performSelectorOnMainThread: @selector(imageRequestFinished)];
};
ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror)
{
NSLog(@"Error fetching photo: %@",[myerror localizedDescription]);
[self performSelectorOnMainThread: @selector(imageRequestFinished)];
};
// create library and set callbacks
ALAssetsLibrary *al = [DetailsViewController defaultAssetsLibrary];
[al assetForURL:asseturl
resultBlock:resultblock
failureBlock:failureblock];
}
创建一个新的回调方法:
- (void) imageRequestFinished
{
mUnfinishedRequests--;
if(mUnfinishedRequests <= 0)
{
[self sendMail];
}
}
在获取图像后,还有一种最终发送邮件的额外方法:
- (void) sendMail
{
// crate mailcomposer etc
[...]
// attach images
for (UIImage *photo in mArrayForImages )
{
NSData *imageData = UIImageJPEGRepresentation(photo, 0.5);
[mailer addAttachmentData:imageData mimeType:@"image/jpeg" fileName:[NSString stringWithFormat:@"a.jpg"]];
}
// send mail
[...]
}
关于iphone - MFMailComposeViewController : Attaching Images from Photo Gallery,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9587485/