Iphone iOS下载并在应用程序内保存图像
我是否可以从网站下载图像并将其永久保存在我的应用程序中？我真的不知道，但这将是我的应用程序的一个很好的功能。带缓存的异步下载图像Iphone iOS下载并在应用程序内保存图像,iphone,cocoa-touch,ios,ipad,Iphone,Cocoa Touch,Ios,Ipad,我是否可以从网站下载图像并将其永久保存在我的应用程序中？我真的不知道，但这将是我的应用程序的一个很好的功能。带缓存的异步下载图像 您无法在应用程序包中保存任何内容，但可以使用+[NSData dataWithContentsOfURL:将图像存储在应用程序的文档目录中，例如： NSData *imageData = [NSData dataWithContentsOfURL:myImageURL]; NSString *imagePath = [[NSSearchPathForDirector
您无法在应用程序包中保存任何内容，但可以使用
+[NSData dataWithContentsOfURL:NSData *imageData = [NSData dataWithContentsOfURL:myImageURL];
NSString *imagePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"/myImage.png"];
[imageData writeToFile:imagePath atomically:YES];
不完全是永久的，但至少在用户删除应用程序之前，它会一直存在。这是主要概念。玩得开心；）
由于我们现在使用IO5，您不再需要将图像写入磁盘。
现在可以在coredata二进制属性上设置“允许外部存储”。 根据苹果发布说明，其含义如下： 诸如图像缩略图之类的小数据值可以有效地存储在存储库中 数据库，但大型照片或其他媒体最好由 文件系统。现在可以指定托管 对象属性可以存储为外部记录-请参阅 启用后，如果 它应该将数据直接保存在数据库中，或者将URI存储到 它为您管理的单独文件。您不能基于 如果使用此选项，则为二进制数据属性的内容
虽然这里的其他答案确实有效，它们确实不是应该在生产代码中使用的解决方案。（至少不需要修改） 问题 这些答案的问题是，如果它们是按原样实现的，并且不是从后台线程调用的，那么它们将在下载和保存图像时阻止主线程。这是坏的 如果主线程被阻止，在图像下载/保存完成之前，不会进行UI更新。作为这意味着什么的一个例子，假设您向应用程序添加一个UIActivityIndicatorView，以向用户显示下载仍在进行中（我将在整个回答中以此为例），大致控制流程如下：
+[NSData dataWithContentsOfURL:][/code>0x8badf00dNSURL *url = [NSURL URLWithString:@"http://example.com/yourImage.png"];
NSData *data = [NSData dataWithContentsOfURL:url];
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
path = [path stringByAppendingString:@"/yourLocalImage.png"];
[data writeToFile:path atomically:YES];
- (NSURL *)documentsDirectoryURL
{
NSError *error = nil;
NSURL *url = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory
inDomain:NSUserDomainMask
appropriateForURL:nil
create:NO
error:&error];
if (error) {
// Figure out what went wrong and handle the error.
}
return url;
}
// Start the activity indicator before moving off the main thread
[self.activityIndicator startAnimating];
// Move off the main thread to start our blocking tasks.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Create the image URL from a known string.
NSURL *imageURL = [NSURL URLWithString:@"http://www.google.com/images/srpr/logo3w.png"];
NSError *downloadError = nil;
// Create an NSData object from the contents of the given URL.
NSData *imageData = [NSData dataWithContentsOfURL:imageURL
options:kNilOptions
error:&downloadError];
// ALWAYS utilize the error parameter!
if (downloadError) {
// Something went wrong downloading the image. Figure out what went wrong and handle the error.
// Don't forget to return to the main thread if you plan on doing UI updates here as well.
dispatch_async(dispatch_get_main_queue(), ^{
[self.activityIndicator stopAnimating];
NSLog(@"%@",[downloadError localizedDescription]);
});
} else {
// Get the path of the application's documents directory.
NSURL *documentsDirectoryURL = [self documentsDirectoryURL];
// Append the desired file name to the documents directory path.
NSURL *saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:@"GCD.png"];
NSError *saveError = nil;
BOOL writeWasSuccessful = [imageData writeToURL:saveLocation
options:kNilOptions
error:&saveError];
// Successful or not we need to stop the activity indicator, so switch back the the main thread.
dispatch_async(dispatch_get_main_queue(), ^{
// Now that we're back on the main thread, you can make changes to the UI.
// This is where you might display the saved image in some image view, or
// stop the activity indicator.
// Check if saving the file was successful, once again, utilizing the error parameter.
if (writeWasSuccessful) {
// Get the saved image data from the file.
NSData *imageData = [NSData dataWithContentsOfURL:saveLocation];
// Set the imageView's image to the image we just saved.
self.imageView.image = [UIImage imageWithData:imageData];
} else {
NSLog(@"%@",[saveError localizedDescription]);
// Something went wrong saving the file. Figure out what went wrong and handle the error.
}
[self.activityIndicator stopAnimating];
});
}
});
// Start the activity indicator before starting the download task.
[self.activityIndicator startAnimating];
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
// Use a session with a custom configuration
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];
// Create the image URL from some known string.
NSURL *imageURL = [NSURL URLWithString:@"http://www.google.com/images/srpr/logo3w.png"];
// Create the download task passing in the URL of the image.
NSURLSessionDownloadTask *task = [session downloadTaskWithURL:imageURL completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
// Get information about the response if neccessary.
if (error) {
NSLog(@"%@",[error localizedDescription]);
// Something went wrong downloading the image. Figure out what went wrong and handle the error.
// Don't forget to return to the main thread if you plan on doing UI updates here as well.
dispatch_async(dispatch_get_main_queue(), ^{
[self.activityIndicator stopAnimating];
});
} else {
NSError *openDataError = nil;
NSData *downloadedData = [NSData dataWithContentsOfURL:location
options:kNilOptions
error:&openDataError];
if (openDataError) {
// Something went wrong opening the downloaded data. Figure out what went wrong and handle the error.
// Don't forget to return to the main thread if you plan on doing UI updates here as well.
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(@"%@",[openDataError localizedDescription]);
[self.activityIndicator stopAnimating];
});
} else {
// Get the path of the application's documents directory.
NSURL *documentsDirectoryURL = [self documentsDirectoryURL];
// Append the desired file name to the documents directory path.
NSURL *saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:@"NSURLSession.png"];
NSError *saveError = nil;
BOOL writeWasSuccessful = [downloadedData writeToURL:saveLocation
options:kNilOptions
error:&saveError];
// Successful or not we need to stop the activity indicator, so switch back the the main thread.
dispatch_async(dispatch_get_main_queue(), ^{
// Now that we're back on the main thread, you can make changes to the UI.
// This is where you might display the saved image in some image view, or
// stop the activity indicator.
// Check if saving the file was successful, once again, utilizing the error parameter.
if (writeWasSuccessful) {
// Get the saved image data from the file.
NSData *imageData = [NSData dataWithContentsOfURL:saveLocation];
// Set the imageView's image to the image we just saved.
self.imageView.image = [UIImage imageWithData:imageData];
} else {
NSLog(@"%@",[saveError localizedDescription]);
// Something went wrong saving the file. Figure out what went wrong and handle the error.
}
[self.activityIndicator stopAnimating];
});
}
}
}];
// Tell the download task to resume (start).
[task resume];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration
delegate:self
delegateQueue:[NSOperationQueue mainQueue]];
// Use the default session configuration for the manager (background downloads must use the delegate APIs)
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
// Use AFNetworking's NSURLSessionManager to manage a NSURLSession.
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
// Create the image URL from some known string.
NSURL *imageURL = [NSURL URLWithString:@"http://www.google.com/images/srpr/logo3w.png"];
// Create a request object for the given URL.
NSURLRequest *request = [NSURLRequest requestWithURL:imageURL];
// Create a pointer for a NSProgress object to be used to determining download progress.
NSProgress *progress = nil;
// Create the callback block responsible for determining the location to save the downloaded file to.
NSURL *(^destinationBlock)(NSURL *targetPath, NSURLResponse *response) = ^NSURL *(NSURL *targetPath, NSURLResponse *response) {
// Get the path of the application's documents directory.
NSURL *documentsDirectoryURL = [self documentsDirectoryURL];
NSURL *saveLocation = nil;
// Check if the response contains a suggested file name
if (response.suggestedFilename) {
// Append the suggested file name to the documents directory path.
saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:response.suggestedFilename];
} else {
// Append the desired file name to the documents directory path.
saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:@"AFNetworking.png"];
}
return saveLocation;
};
// Create the completion block that will be called when the image is done downloading/saving.
void (^completionBlock)(NSURLResponse *response, NSURL *filePath, NSError *error) = ^void (NSURLResponse *response, NSURL *filePath, NSError *error) {
dispatch_async(dispatch_get_main_queue(), ^{
// There is no longer any reason to observe progress, the download has finished or cancelled.
[progress removeObserver:self
forKeyPath:NSStringFromSelector(@selector(fractionCompleted))];
if (error) {
NSLog(@"%@",error.localizedDescription);
// Something went wrong downloading or saving the file. Figure out what went wrong and handle the error.
} else {
// Get the data for the image we just saved.
NSData *imageData = [NSData dataWithContentsOfURL:filePath];
// Get a UIImage object from the image data.
self.imageView.image = [UIImage imageWithData:imageData];
}
});
};
// Create the download task for the image.
NSURLSessionDownloadTask *task = [manager downloadTaskWithRequest:request
progress:&progress
destination:destinationBlock
completionHandler:completionBlock];
// Start the download task.
[task resume];
// Begin observing changes to the download task's progress to display to the user.
[progress addObserver:self
forKeyPath:NSStringFromSelector(@selector(fractionCompleted))
options:NSKeyValueObservingOptionNew
context:NULL];
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
// We only care about updates to fractionCompleted
if ([keyPath isEqualToString:NSStringFromSelector(@selector(fractionCompleted))]) {
NSProgress *progress = (NSProgress *)object;
// localizedDescription gives a string appropriate for display to the user, i.e. "42% completed"
self.progressLabel.text = progress.localizedDescription;
} else {
[super observeValueForKeyPath:keyPath
ofObject:object
change:change
context:context];
}
}
// Create the destination closure to pass to the download request. I haven't done anything with them
// here but you can utilize the parameters to make adjustments to the file name if neccessary.
let destination = { (url: NSURL!, response: NSHTTPURLResponse!) -> NSURL in
var error: NSError?
// Get the documents directory
let documentsDirectory = NSFileManager.defaultManager().URLForDirectory(.DocumentDirectory,
inDomain: .UserDomainMask,
appropriateForURL: nil,
create: false,
error: &error
)
if let error = error {
// This could be bad. Make sure you have a backup plan for where to save the image.
println("\(error.localizedDescription)")
}
// Return a destination of .../Documents/Alamofire.png
return documentsDirectory!.URLByAppendingPathComponent("Alamofire.png")
}
Alamofire.download(.GET, "http://www.google.com/images/srpr/logo3w.png", destination)
.validate(statusCode: 200..<299) // Require the HTTP status code to be in the Successful range.
.validate(contentType: ["image/png"]) // Require the content type to be image/png.
.progress { (bytesRead, totalBytesRead, totalBytesExpectedToRead) in
// Create an NSProgress object to represent the progress of the download for the user.
let progress = NSProgress(totalUnitCount: totalBytesExpectedToRead)
progress.completedUnitCount = totalBytesRead
dispatch_async(dispatch_get_main_queue()) {
// Move back to the main thread and update some progress label to show the user the download is in progress.
self.progressLabel.text = progress.localizedDescription
}
}
.response { (request, response, _, error) in
if error != nil {
// Something went wrong. Handle the error.
} else {
// Open the newly saved image data.
if let imageData = NSData(contentsOfURL: destination(nil, nil)) {
dispatch_async(dispatch_get_main_queue()) {
// Move back to the main thread and add the image to your image view.
self.imageView.image = UIImage(data: imageData)
}
}
}
}
[self setImageWithURL:user.user_ProfilePicturePath toControl:cell.imgView];
-(void)setImageWithURL:(NSURL*)url toControl:(id)ctrl
{
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request imageProcessingBlock:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
if (image) {
if([ctrl isKindOfClass:[UIButton class]])
{
UIButton btn =(UIButton)ctrl;
[btn setBackgroundImage:image forState:UIControlStateNormal];
}
else
{
UIImageView imgView = (UIImageView)ctrl;
imgView.image = image;
}
}
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
NSLog(@"No Image");
}];
[operation start];}
- (void)viewDidLoad {
[super viewDidLoad];
[self performSelectorInBackground:@selector(loadImageIntoMemory) withObject:nil];
}
- (void)loadImageIntoMemory {
NSString *temp_Image_String = [[NSString alloc] initWithFormat:@"http://yourwebsite.com/MyImageName.jpg"];
NSURL *url_For_Ad_Image = [[NSURL alloc] initWithString:temp_Image_String];
NSData *data_For_Ad_Image = [[NSData alloc] initWithContentsOfURL:url_For_Ad_Image];
UIImage *temp_Ad_Image = [[UIImage alloc] initWithData:data_For_Ad_Image];
[self saveImage:temp_Ad_Image];
UIImageView *imageViewForAdImages = [[UIImageView alloc] init];
imageViewForAdImages.frame = CGRectMake(0, 0, 320, 50);
imageViewForAdImages.image = [self loadImage];
[self.view addSubview:imageViewForAdImages];
}
- (void)saveImage: (UIImage*)image {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent: @"MyImageName.jpg" ];
NSData* data = UIImagePNGRepresentation(image);
[data writeToFile:path atomically:YES];
}
- (UIImage*)loadImage {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:@"MyImageName.jpg" ];
UIImage* image = [UIImage imageWithContentsOfFile:path];
return image;
}
- (void)downloadImageWithURL:(NSURL *)url completionBlock:(void (^)(BOOL succeeded, UIImage *image))completionBlock
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
if ( !error )
{
UIImage *image = [[UIImage alloc] initWithData:data];
completionBlock(YES,image);
} else{
completionBlock(NO,nil);
}
}];
}
NSURL *imageUrl = //...
[[MyUtilManager sharedInstance] downloadImageWithURL:[NSURL URLWithString:imageURL] completionBlock:^(BOOL succeeded, UIImage *image) {
//Here you can save the image permanently, update UI and do what you want...
}];
+ (void)downloadImageWithURL:(NSURL *)url completionBlock:(void (^)(BOOL succeeded, UIImage *image))completionBlock
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
if ( !error )
{
UIImage *image = [[UIImage alloc] initWithData:data];
completionBlock(YES,image);
} else{
completionBlock(NO,nil);
}
}];
}
+(void)downloadImageWithURL:(NSURL *)url completionBlock:(void (^)(BOOL succeeded, UIImage *image))completionBlock
{
NSURLSessionDataTask* _sessionTask = [[NSURLSession sharedSession] dataTaskWithRequest:[NSURLRequest requestWithURL:url]
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
if (error != nil)
{
if ([error code] == NSURLErrorAppTransportSecurityRequiresSecureConnection)
{
completionBlock(NO,nil);
}
}
else
{
[[NSOperationQueue mainQueue] addOperationWithBlock: ^{
dispatch_async(dispatch_get_main_queue(), ^{
UIImage *image = [[UIImage alloc] initWithData:data];
completionBlock(YES,image);
});
}];
}
}];
[_sessionTask resume];
}
func dowloadAndSaveFile(from url: URL) {
let destination: DownloadRequest.DownloadFileDestination = { _, _ in
var documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
documentsURL.appendPathComponent(url.lastPathComponent)
return (documentsURL, [.removePreviousFile])
}
let request = SessionManager.default.download(url, method: .get, to: destination)
request.validate().responseData { response in
switch response.result {
case .success:
if let destinationURL = response.destinationURL {
print(destinationURL)
}
case .failure(let error):
print(error.localizedDescription)
}
}
}