New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/platform/background_downloader_ios.h

@@ -0,0 +1,23 @@
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+typedef void (^DownloadCompleteBlock)(NSError *_Nullable error);
+typedef void (^DownloadProgressBlock)(int64_t bytesWritten, int64_t bytesExpected);
+
+/// Note: this class is NOT thread-safe and must be used from main thread only.
+@interface BackgroundDownloader : NSObject
+
+@property(copy, nonatomic, nullable) void (^backgroundCompletionHandler)(void);
+
++ (BackgroundDownloader *)sharedBackgroundMapDownloader;
+
+- (NSUInteger)downloadWithUrl:(NSURL *)url
+                   completion:(DownloadCompleteBlock)completion
+                     progress:(DownloadProgressBlock)progress;
+- (void)cancelTaskWithIdentifier:(NSUInteger)taskIdentifier;
+- (void)clear;
+
+@end
+
+NS_ASSUME_NONNULL_END