Classes/AssetBrowser/AssetBrowserController.m
/* |
File: AssetBrowserController.m |
Abstract: UIViewController allowing asset selection. |
Version: 1.3 |
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*/ |
#import "AssetBrowserController.h" |
#import "AssetBrowserSource.h" |
#import <AVFoundation/AVFoundation.h> |
#import <CoreMedia/CoreMedia.h> |
#import <MobileCoreServices/UTCoreTypes.h> |
/* Generating thumbnails is expensive and requires a lot of resources. |
If we do this while scrolling our framerate is affected. If your app presents a persistent |
media library it may make sense to cache thumbnails and metadata in a database. */ |
#define ONLY_GENERATE_THUMBS_AND_TITLES_WHEN_NOT_SCROLLING 1 |
@interface AssetBrowserController () <AssetBrowserSourceDelegate, UIScrollViewDelegate, UITableViewDelegate, UITableViewDataSource> |
@property (nonatomic, copy) NSArray *assetSources; |
- (void)configureCell:(UITableViewCell*)cell forIndexPath:(NSIndexPath *)indexPath; |
- (void)updateActiveAssetSources; |
- (void)enableThumbnailAndTitleGeneration; |
- (void)disableThumbnailAndTitleGeneration; |
- (void)generateThumbnailsAndTitles; |
- (void)cancelAction; |
@end |
@implementation AssetBrowserController |
@synthesize assetSources; |
@synthesize delegate; |
enum { |
AssetBrowserScrollDirectionDown, |
AssetBrowserScrollDirectionUp |
}; |
#pragma mark - |
#pragma mark Initialization |
- (id)initWithSourceType:(AssetBrowserSourceType)sourceType modalPresentation:(BOOL)modalPresentation; |
{ |
if ((self = [super initWithStyle:UITableViewStylePlain])) |
{ |
browserSourceType = sourceType; |
if ((browserSourceType & AssetBrowserSourceTypeAll) == 0) { |
NSLog(@"AssetBrowserController: Invalid sourceType"); |
return nil; |
} |
[self setEdgesForExtendedLayout:UIRectEdgeAll]; |
thumbnailScale = [[UIScreen mainScreen] scale]; |
activeAssetSources = [[NSMutableArray alloc] initWithCapacity:0]; |
isModal = modalPresentation; |
// Okay now generate the list of Assets to be displayed. |
// This should be relatively quick since we are not creating assets or thumbnails. |
NSMutableArray *sources = [NSMutableArray arrayWithCapacity:0]; |
if (browserSourceType & AssetBrowserSourceTypeFileSharing) { |
[sources addObject:[AssetBrowserSource assetBrowserSourceOfType:AssetBrowserSourceTypeFileSharing]]; |
} |
if (browserSourceType & AssetBrowserSourceTypeCameraRoll) { |
[sources addObject:[AssetBrowserSource assetBrowserSourceOfType:AssetBrowserSourceTypeCameraRoll]]; |
} |
if (browserSourceType & AssetBrowserSourceTypeIPodLibrary) { |
[sources addObject:[AssetBrowserSource assetBrowserSourceOfType:AssetBrowserSourceTypeIPodLibrary]]; |
} |
self.assetSources = sources; |
if ([sources count] == 1) { |
singleSourceTypeMode = YES; |
self.title = [[self.assetSources objectAtIndex:0] name]; |
} |
else { |
self.title = NSLocalizedString(@"Media", nil); |
} |
} |
return self; |
} |
#pragma mark - |
#pragma mark View lifecycle |
- (void)viewDidLoad |
{ |
[super viewDidLoad]; |
self.tableView.rowHeight = 65.0; // 1 point is for the divider, we want our thumbnails to have an even height. |
if (!singleSourceTypeMode) |
self.tableView.sectionHeaderHeight = 22.0; |
// We wait until the scroll view has finished decelerating to generate thumbnails so make the deceleration a bit faster than normal. |
float decel = UIScrollViewDecelerationRateNormal - (UIScrollViewDecelerationRateNormal - UIScrollViewDecelerationRateFast)/2.0; |
self.tableView.decelerationRate = decel; |
if (isModal && (self.modalPresentationStyle == UIModalPresentationFullScreen)) { |
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel |
target:self action:@selector(cancelAction)]; |
} |
} |
- (void)viewWillAppear:(BOOL)animated |
{ |
[super viewWillAppear:animated]; |
if (isModal && (self.modalPresentationStyle == UIModalPresentationFullScreen)) { |
lastStatusBarStyle = [UIApplication sharedApplication].statusBarStyle; |
if ( lastStatusBarStyle != UIStatusBarStyleLightContent ) { |
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent animated:animated]; |
} |
} |
lastTableViewYContentOffset = self.tableView.contentOffset.y; |
lastTableViewScrollDirection = AssetBrowserScrollDirectionDown; |
if (haveBuiltSourceLibraries) |
return; |
haveBuiltSourceLibraries = YES; |
for (AssetBrowserSource *source in self.assetSources) { |
[source buildSourceLibrary]; |
} |
[self updateActiveAssetSources]; |
[self.tableView reloadData]; |
for (AssetBrowserSource *source in self.assetSources) { |
source.delegate = self; |
} |
} |
- (void)cancelAction |
{ |
if ([self.delegate respondsToSelector:@selector(assetBrowserDidCancel:)]) { |
[self.delegate assetBrowserDidCancel:self]; |
} |
} |
- (void)viewDidAppear:(BOOL)animated |
{ |
[super viewDidAppear:animated]; |
[self enableThumbnailAndTitleGeneration]; |
[self generateThumbnailsAndTitles]; |
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow]; |
if (indexPath) { |
[self.tableView deselectRowAtIndexPath:indexPath animated:YES]; |
} |
} |
- (void)viewWillDisappear:(BOOL)animated { |
[super viewWillDisappear:animated]; |
[self disableThumbnailAndTitleGeneration]; |
if (isModal && (self.modalPresentationStyle == UIModalPresentationFullScreen)) { |
if ( lastStatusBarStyle != UIStatusBarStyleLightContent ) { |
[[UIApplication sharedApplication] setStatusBarStyle:lastStatusBarStyle animated:animated]; |
} |
} |
} |
- (void)viewDidDisappear:(BOOL)animated { |
[super viewDidDisappear:animated]; |
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow]; |
if (indexPath) |
[self.tableView deselectRowAtIndexPath:indexPath animated:NO]; |
} |
- (void)clearSelection |
{ |
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow]; |
if (indexPath) |
[self.tableView deselectRowAtIndexPath:indexPath animated:YES]; |
} |
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation |
{ |
if ( [UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPad ) { |
return YES; |
} |
return (interfaceOrientation == UIInterfaceOrientationPortrait); |
} |
- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation |
{ |
// If a thumbnail finished while we were rotating then its cell might not have been updated, but the cell could still be cached. |
for (UITableViewCell *visibleCell in [self.tableView visibleCells]) { |
NSIndexPath *indexPath = [self.tableView indexPathForCell:visibleCell]; |
[self configureCell:visibleCell forIndexPath:indexPath]; |
} |
} |
#pragma mark - |
#pragma mark Table view data source |
- (void)updateActiveAssetSources |
{ |
[activeAssetSources removeAllObjects]; |
for (AssetBrowserSource *source in self.assetSources) { |
if ( ([source.items count] > 0) ) { |
[activeAssetSources addObject:source]; |
} |
} |
} |
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView |
{ |
return [activeAssetSources count]; |
} |
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section |
{ |
if (singleSourceTypeMode) |
return nil; |
AssetBrowserSource *source = [activeAssetSources objectAtIndex:section]; |
NSString *name = [source.items count] > 0 ? source.name : nil; |
return name; |
} |
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { |
NSInteger numRows = 0; |
numRows = [[[activeAssetSources objectAtIndex:section] items] count]; |
return numRows; |
} |
- (void)configureCell:(UITableViewCell*)cell forIndexPath:(NSIndexPath *)indexPath |
{ |
if ( cell == nil) |
return; |
AssetBrowserSource *source = [activeAssetSources objectAtIndex:indexPath.section]; |
AssetBrowserItem *item = [[source items] objectAtIndex:indexPath.row]; |
cell.textLabel.text = item.title; |
UIImage *thumb = item.thumbnailImage; |
if ( !thumb || !item.haveRichestTitle ) { |
[self generateThumbnailsAndTitles]; |
} |
if (!thumb) { |
thumb = [item placeHolderImage]; |
} |
cell.imageView.image = thumb; |
} |
// Customize the appearance of table view cells. |
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath |
{ |
static NSString *CellIdentifier = @"Cell"; |
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; |
if (cell == nil) { |
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; |
cell.textLabel.font = [UIFont boldSystemFontOfSize:14.0]; |
cell.accessoryType = isModal ? UITableViewCellAccessoryNone : UITableViewCellAccessoryDisclosureIndicator; |
} |
[self configureCell:cell forIndexPath:indexPath]; |
return cell; |
} |
#pragma mark - |
#pragma mark Table view delegate |
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath |
{ |
AssetBrowserItem *selectedItem = [[(AssetBrowserSource*)[activeAssetSources objectAtIndex:indexPath.section] items] objectAtIndex:indexPath.row]; |
if ([self.delegate respondsToSelector:@selector(assetBrowser:didChooseItem:)]) { |
AssetBrowserItem *selectedItemCopy = [selectedItem copy]; |
[self.delegate assetBrowser:self didChooseItem:selectedItemCopy]; |
} |
} |
#pragma mark - |
#pragma mark Asset Library Delegate |
- (void)assetBrowserSourceItemsDidChange:(AssetBrowserSource*)source |
{ |
[self updateActiveAssetSources]; |
[self.tableView reloadData]; |
} |
#pragma mark - |
#pragma mark Thumbnail Generation |
- (void)updateCellForBrowserItemIfVisible:(AssetBrowserItem*)browserItem |
{ |
NSArray *visibleIndexPaths = [self.tableView indexPathsForVisibleRows]; |
for (NSIndexPath *indexPath in visibleIndexPaths) { |
AssetBrowserItem *visibleBrowserItem = [[[activeAssetSources objectAtIndex:indexPath.section] items] objectAtIndex:indexPath.row]; |
if ([browserItem isEqual:visibleBrowserItem]) { |
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath]; |
[self configureCell:cell forIndexPath:indexPath]; |
[cell setNeedsLayout]; |
break; |
} |
} |
} |
- (void)thumbnailsAndTitlesTask |
{ |
if (! thumbnailAndTitleGenerationEnabled) { |
thumbnailAndTitleGenerationIsRunning = NO; |
return; |
} |
thumbnailAndTitleGenerationIsRunning = YES; |
NSArray *visibleIndexPaths = [self.tableView indexPathsForVisibleRows]; |
id objOrEnumerator = (lastTableViewScrollDirection == AssetBrowserScrollDirectionDown) ? (id)visibleIndexPaths : (id)[visibleIndexPaths reverseObjectEnumerator]; |
for (NSIndexPath *path in objOrEnumerator) |
{ |
NSArray *assetItemsInSection = [[activeAssetSources objectAtIndex:path.section] items]; |
AssetBrowserItem *assetItem = ((NSInteger)[assetItemsInSection count] > path.row) ? [assetItemsInSection objectAtIndex:path.row] : nil; |
if (assetItem) { |
__block NSInteger runningRequests = 0; |
if (assetItem.thumbnailImage == nil) { |
CGFloat targetHeight = self.tableView.rowHeight -1.0; // The contentView is one point smaller than the cell because of the divider. |
targetHeight *= thumbnailScale; |
CGFloat targetAspectRatio = 1.5; |
CGSize targetSize = CGSizeMake(targetHeight*targetAspectRatio, targetHeight); |
runningRequests++; |
[assetItem generateThumbnailAsynchronouslyWithSize:targetSize fillMode:AssetBrowserItemFillModeCrop completionHandler:^(UIImage *thumbnail) |
{ |
runningRequests--; |
if (runningRequests == 0) { |
[self updateCellForBrowserItemIfVisible:assetItem]; |
// Continue generating until all thumbnails/titles in range have been finished. |
[self thumbnailsAndTitlesTask]; |
} |
}]; |
} |
if (!assetItem.haveRichestTitle) { |
runningRequests++; |
[assetItem generateTitleFromMetadataAsynchronouslyWithCompletionHandler:^(NSString *title){ |
runningRequests--; |
if (runningRequests == 0) { |
[self updateCellForBrowserItemIfVisible:assetItem]; |
// Continue generating until all thumbnails/titles in range have been finished. |
[self thumbnailsAndTitlesTask]; |
} |
}]; |
} |
// If we are generating a title or thumbnail then wait until that returns to generate the next one. |
if ( runningRequests > 0 ) |
return; |
} |
} |
thumbnailAndTitleGenerationIsRunning = NO; |
return; |
} |
- (void)enableThumbnailAndTitleGeneration |
{ |
thumbnailAndTitleGenerationEnabled = YES; |
} |
- (void)disableThumbnailAndTitleGeneration |
{ |
thumbnailAndTitleGenerationEnabled = NO; |
} |
- (void)generateThumbnailsAndTitles |
{ |
if (! thumbnailAndTitleGenerationEnabled) { |
return; |
} |
if (! thumbnailAndTitleGenerationIsRunning) { |
/* Run on the next run loop iteration. We may be called from with configureCell: and we don't want to slow down table view display. */ |
thumbnailAndTitleGenerationIsRunning = YES; |
dispatch_async(dispatch_get_main_queue(), ^(void) { |
[self thumbnailsAndTitlesTask]; |
}); |
} |
} |
#pragma mark - |
#pragma mark Deferred image loading (UIScrollViewDelegate) |
#if ONLY_GENERATE_THUMBS_AND_TITLES_WHEN_NOT_SCROLLING |
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView |
{ |
[self disableThumbnailAndTitleGeneration]; |
} |
// Load images for all onscreen rows when scrolling is finished |
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate |
{ |
if (!decelerate) { |
[self enableThumbnailAndTitleGeneration]; |
[self generateThumbnailsAndTitles]; |
} |
} |
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView |
{ |
[self enableThumbnailAndTitleGeneration]; |
[self generateThumbnailsAndTitles]; |
} |
#endif //ONLY_GENERATE_THUMBS_AND_TITLES_WHEN_NOT_SCROLLING |
- (void)scrollViewDidScroll:(UIScrollView *)scrollView |
{ |
CGFloat newOffset = scrollView.contentOffset.y; |
CGFloat oldOffset = lastTableViewYContentOffset; |
CGFloat offsetAmount = newOffset-oldOffset; |
// Only update the scroll direction if we've passed some threshold (8 points). |
if ( fabs(offsetAmount) > 8.0 ) { |
if (offsetAmount > 0.0) |
lastTableViewScrollDirection = AssetBrowserScrollDirectionDown; |
else if (newOffset < oldOffset) |
lastTableViewScrollDirection = AssetBrowserScrollDirectionUp; |
lastTableViewYContentOffset = newOffset; |
} |
} |
#pragma mark - |
#pragma mark Memory management |
- (void)didReceiveMemoryWarning { |
// Releases the view if it doesn't have a superview. |
[super didReceiveMemoryWarning]; |
// Get rid of AVAsset and thumbnail caches for items which aren't on screen. |
NSLog(@"%@ memory warning, clearing asset and thumbnail caches", self); |
NSArray *visibleIndexPaths = [self.tableView indexPathsForVisibleRows]; |
NSUInteger section = 0; |
NSUInteger row = 0; |
for (AssetBrowserSource *source in activeAssetSources) { |
row = 0; |
for (AssetBrowserItem *item in [source items]) { |
NSIndexPath *path = [NSIndexPath indexPathForRow:row inSection:section]; |
if (![visibleIndexPaths containsObject:path]) { |
[item clearAssetCache]; |
[item clearThumbnailCache]; |
} |
row++; |
} |
section++; |
} |
} |
- (void)dealloc |
{ |
delegate = nil; |
} |
@end |
@implementation UINavigationController (AssetBrowserConvenienceMethods) |
+ (UINavigationController*)modalAssetBrowserControllerWithSourceType:(AssetBrowserSourceType)sourceType delegate:(id <AssetBrowserControllerDelegate>)delegate |
{ |
AssetBrowserController *browser = [[AssetBrowserController alloc] initWithSourceType:sourceType modalPresentation:YES]; |
browser.delegate = delegate; |
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:browser]; |
[navController.navigationBar setBarStyle:UIBarStyleBlack]; |
[navController.navigationBar setTranslucent:YES]; |
return navController; |
} |
@end |
@implementation UITabBarController (AssetBrowserConvenienceMethods) |
+ (UITabBarController*)tabbedModalAssetBrowserControllerWithSourceType:(AssetBrowserSourceType)sourceType delegate:(id <AssetBrowserControllerDelegate>)delegate |
{ |
UITabBarController *tabBarController = [[UITabBarController alloc] init]; |
NSMutableArray *assetBrowserControllers = [NSMutableArray arrayWithCapacity:0]; |
if (sourceType & AssetBrowserSourceTypeCameraRoll) { |
[assetBrowserControllers addObject:[UINavigationController modalAssetBrowserControllerWithSourceType:AssetBrowserSourceTypeCameraRoll delegate:delegate]]; |
} |
if (sourceType & AssetBrowserSourceTypeFileSharing) { |
[assetBrowserControllers addObject:[UINavigationController modalAssetBrowserControllerWithSourceType:AssetBrowserSourceTypeFileSharing delegate:delegate]]; |
} |
if (sourceType & AssetBrowserSourceTypeIPodLibrary) { |
[assetBrowserControllers addObject:[UINavigationController modalAssetBrowserControllerWithSourceType:AssetBrowserSourceTypeIPodLibrary delegate:delegate]]; |
} |
tabBarController.viewControllers = assetBrowserControllers; |
return tabBarController; |
} |
@end |
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