Saving and viewing files in iOS - ios

Question

I'm getting base64-encoded file content from server. Then I'm writing data into file. I checked that file is not empty after that, it means data was successfully written to file. But when I'm trying to present this file, all I get is an empty view. So what am I doin' wrong?
enter image description here
[f getFile:^(NSString * _Nonnull string) {
NSString *docsDir;
NSArray *dirPaths;
NSData *content = [string dataUsingEncoding:NSUTF8StringEncoding];
dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];
NSString *databasePath = [[NSString alloc] initWithString:[docsDir stringByAppendingPathComponent:#"hill.jpg"]];
[content writeToFile:databasePath atomically:YES];
if ([[NSFileManager defaultManager] fileExistsAtPath:databasePath]){
NSURL *url = [NSURL fileURLWithPath:databasePath];
UIDocumentInteractionController *documentInteractionController =[UIDocumentInteractionController interactionControllerWithURL:url];
documentInteractionController.delegate = self;
[documentInteractionController presentPreviewAnimated:YES];
}
} Error:^(NSString * _Nonnull errorMessage) {
}];

Answer 1

Edited your code snippet, Try it
[f getFile:^(NSString * _Nonnull string) {
NSString *docsDir;
NSArray *dirPaths;
NSData *content = [[NSData alloc] initWithBase64EncodedString: string options:0];
dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];
NSString *databasePath = [[NSString alloc] initWithString:[docsDir stringByAppendingPathComponent:#"hill.jpg"]];
[content writeToFile:databasePath atomically:YES];
if ([[NSFileManager defaultManager] fileExistsAtPath:databasePath]){
NSURL *url = [NSURL fileURLWithPath:databasePath];
UIDocumentInteractionController *documentInteractionController =[UIDocumentInteractionController interactionControllerWithURL:url];
documentInteractionController.delegate = self;
[documentInteractionController presentPreviewAnimated:YES];
}
} Error:^(NSString * _Nonnull errorMessage) {
}];

Answer 2

From your code, I see you save a string into a an image file (hill.jpg). The UIDocumentInteractionController read file base on their extension, so they can't read this file. I think if you change your file name to hill.txt, your code could work. Hope this helps.

Answer 3

As you say, the content gets from the server are base64-encode, so you need to decode it.
NSData *imageContent = [[NSData alloc] initWithBase64EncodedString:string options:kNilOptions];
if (imageContent) {
// save to file
}