Created
January 13, 2014 10:05
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Demo for a NSAttributedString / HTML parsing issue on iOS 7
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| @import UIKit; | |
| #pragma mark - Main View Controller | |
| @interface ViewController : UITableViewController | |
| @end | |
| @implementation ViewController | |
| // A simple TableViewController with a large number of cell | |
| // | |
| - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return 10000; } | |
| // A small HTML fragment is parsed and set as the attributed title for each cell | |
| // | |
| - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath | |
| { | |
| UITableViewCell * cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil]; | |
| NSString * htmlSource = [NSString stringWithFormat:@"<html><p>Row <i>%@</i></p></html>", @(indexPath.row)]; | |
| NSAttributedString * attributedText = [[NSAttributedString alloc] initWithData:[htmlSource dataUsingEncoding:NSUTF8StringEncoding] | |
| options:@{NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType} | |
| documentAttributes:nil | |
| error:nil]; | |
| cell.textLabel.attributedText = attributedText; | |
| return cell; | |
| } | |
| - (void) scrollViewDidScroll:(UIScrollView *)scrollView | |
| { | |
| for (NSIndexPath * indexPath in [self.tableView indexPathsForVisibleRows]) { | |
| [self.tableView cellForRowAtIndexPath:indexPath]; // CRASH | |
| // This crashes as soon as you start scrolling. | |
| // | |
| // [self.tableView visibleCells] doesn't match [self.tableView indexPathsForVisibleRows] | |
| // (There are less cells than there are visible rows.) | |
| // | |
| // This happens because HTML parsing uses Webkit in the main thread, which requires running the main runloop in a common mode. | |
| // | |
| // In other words, -scrollViewDidScroll is called inside -cellForRowAtIndexPath. | |
| } | |
| } | |
| @end | |
| #pragma mark - App Setup | |
| @interface AppDelegate : UIResponder <UIApplicationDelegate> | |
| @property (strong, nonatomic) UIWindow *window; | |
| @end | |
| @implementation AppDelegate | |
| - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions | |
| { | |
| self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; | |
| self.window.rootViewController = [ViewController new]; | |
| [self.window makeKeyAndVisible]; | |
| return YES; | |
| } | |
| @end | |
| int main(int argc, char * argv[]) | |
| { | |
| @autoreleasepool { | |
| return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class])); | |
| } | |
| } |
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Filed as rdar://15803156