StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
19473280
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2013-10-20T02:29:27.187
FavoriteCount
0
LastActivityDate
2013-10-20T02:29:27.187
LastEditDate
LastEditorUserId
0
OwnerUserId
2628487
ParentId
12766501
PostTypeId
2
Score
4
ViewCount
0
LastEditorDisplayName
text
Body
My experience below is not directly with <code>UIImage initContentsFromFile:</code> but with <code>UIImage imageWithData</code>, but your question is about UIImage thread safety. I recently had to debug an issue with using <code>[UIImage imageWithData:]</code> that is called from a <code>NSURLConnetionDelegate</code> function <code>connectionDidFinishLoading</code> to download images using several background threads. Since the downloaded images are used for updating the UI, I had to use <code>[NSOperationQueue mainQueue] addOperationWithBlock ...</code> below: <pre><code>- (void) connection:(URLConnection*)connection didReceiveData:(NSData *) data { [imgData appendData:data]; } - (void) connectionDidFinishLoading:(NSURLConnection*)connection { [NSOperationQueue mainQueue] addOperationWithBlock:^{ UIImage *img = [UIImage imageWithData:imgData]; // more code here to update the UI }]; } </code></pre> <ul> <li>When running on an iOS 7.x simulator, <code>img</code> holds a valid image</li> <li>When running on an iOS 7.x device (iPod Touch), <code>img</code> is always <code>nil</code></li> </ul> During a debugging session, I noticed that the issue (temporarily) disappeared when the debugger stepped through each statement one line at a time. My theory is that running in debugger step-mode does not put <code>UIImage</code> to handle concurrent threads running <code>imageWithData</code>. Therefore, I believe that <code>UIImage imageWithData</code> (and perhaps other similar functions) are not thread-safe. Using a <code>@synchronized</code> block seems to solve the issue <pre><code>- (void) connectionDidFinishLoading:(NSURLConnection*)connection { [NSOperationQueue mainQueue] addOperationWithBlock:^{ @synchronized(imgData) { // Run the following in a synchronized block UIImage *img = [UIImage imageWithData:imgData]; } // more code here .... }]; } </code></pre>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POIs creating UIImage thread safe?
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USdlmt
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.