I am using buttons and I assigned tag 0 to 10 . Then I made an action to get the clicked button's tag, and now I want to display the tag in a label . Also I have a cancel button C. If user wants to delete any number, he can click C button that I want to remove number from the label .
This is my screenshot to touch the number
- (void)viewDidLoad {
[super viewDidLoad];
self.title = #"Ezywire";
addnum=[[NSMutableArray alloc]init];
numbber=[[NSString alloc]init];
}
- (IBAction)NumberAction:(id)sender {
NSInteger tagvalue = [sender tag];
NSString *current=[NSString stringWithFormat:#"%ld", (long)tagvalue];
[addnum addObject:current];
NSString *temp;
for ( int i=0; i<[addnum count]; i++) {
numbber=[numbber stringByAppendingString:[addnum objectAtIndex:i]];
}
NSLog(#"data===%#",numbber);
ValueLable.text= numbber;
}
But in the label I am getting repeated number like this. How to implement this.
For example if user enters 2 then in the label
2
then he enters 7 then in the label
27
then he entered 9 then in the label
279
........ like this .
If user clicks C, then it remove from label last value is (last value removed)
27
The problem in your code is that numbber is initialized when the view is loaded, and never gets cleared again. However, each time a button is pressed, the whole addnum of digits gets appended to num again, creating repeated digits.
Fix this by removing num as an instance variable, making it a local to NumberAction: method, and setting it to an empty string every time the number is pressed.
Since you are planning to support the clearing action as well, you should make a private method that combines the digits from addnum array into a string. This way your NumberAction: and ClearAction would share the code that formats the array and sets the label. Your NumberAction: method would append a number and call FormatAndSetLabel, while the ClearAction method would remove the last digit if it is available, and call FormatAndSetLabel as well:
- (IBAction)NumberAction:(id)sender {
NSInteger tagvalue = [sender tag];
NSString *current=[NSString stringWithFormat:#"%ld", (long)tagvalue];
[addnum addObject:current];
[self FormatAndSetLabel];
}
- (IBAction)ClearAction:(id)sender {
if (!addnum.count) return;
[addnum removeLastObject];
[self FormatAndSetLabel];
}
-(void)FormatAndSetLabel {
NSMutableString *temp = [NSMutableString string];
for ( int i=0; i<[addnum count]; i++) {
[temp appendString:addnum[i]];
}
ValueLable.text= temp;
}
Also it might be interesting for you to have a look at Paul's Hegarty Stanford iOS development course (iPad and iPhone Application Development, Fall 2011)
https://itunes.apple.com/ru/itunes-u/ipad-iphone-application-development/id473757255?mt=10
Calculator app is used here as an example. Must see for the beginners.
I've created the master-detail view app using xcode and let xcode generate all the things it should do. I added a few buttons to the TableView and finally hooked up a responder method to these buttons: looking something like this (not all code pasted):
-(IBAction)orderBy:(UIBarButtonItem *)sender
{
int lv_temp = sender.tag;
choice = lv_temp;
switch (lv_temp) {
case 0:
break;
case 1:
{
//This gives us all the different sections available.
typeSections = [Items valueForKeyPath:#"#distinctUnionOfObjects.type"];
//Do some more stuff and create the Dictionary so we hold an array with a key for each section
[ItemsByType2 setObject:ItemsTemp forKey:[NSString stringWithFormat:#"%#", id]];
[ItemsTemp removeAllObjects];
}
The end result is that I finally have a NSDictionary object containing arrays with the section ID's as a key. I'd like to reload these sections so we have a kind of sorting.
The problem is, how and where to call the reloadData of the generated tableView? Looks like the tableView itself is not accessible in the Sender method (which sounds kind of logical to me btw) but I do not know how to call the method so the tableView will call it's methods numberOfSections, RowsPerSection etc (pseudocode btw).
Any ideas?
Cheers!
Laurens
-(IBAction)orderBy:(UIBarButtonItem *)sender {
int lv_temp = sender.tag;
choice = lv_temp;
switch (lv_temp) {
case 0:
break;
case 1: {
//This gives us all the different sections available.
typeSections = [Items valueForKeyPath:#"#distinctUnionOfObjects.type"];
//Do some more stuff and create the Dictionary so we hold an array with a key for each section
[ItemsByType2 setObject:ItemsTemp forKey:[NSString stringWithFormat:#"%#", id]];
[ItemsTemp removeAllObjects];
}
[self.tableView reloadData];
}
(Note: You can probably even answer this without reading any of my code, if you don't feel like reading this novel of a question, I've explained at the bottom)
I have some code that's throwing me a bit off course. It seems like my code is calling [tableView reloadData] before the data is ready, although I set the data before I call reloadData. This is probably a newbie-question, but I have never dealt with this kind of code before, and I'd be very happy if someone could explain to me exactly what is going on, and why some of my code is allowed to jump out of the chronological logic..
My question has nothing to do with GameCenter, I think this is a general Objective-C thing, but I am experiencing it with GameCenter, so even if you don't know anything about GameCenter, you'll probably be able to understand what I'm talking about.
I have a tableViewController, and I am filling the tableView with matches(games) from GameCenter, and showing the names of the opponent(always one opponent in my turn-based-game).
I have put this in my viewDidAppear:
[GKTurnBasedMatch loadMatchesWithCompletionHandler:^(NSArray *matches, NSError *error) {
//Gets an array (*matches) of GKTurnBasedMatches(All matches the local player is involved in)
if(error)
{
NSLog(#"Load matches error: %#", error.description);
return;
}
//putting them in an array
matchList = [[NSArray alloc] initWithArray:matches];
//So far only for testing purposes: I am creating an array for player names:
playerNames = [[NSMutableArray alloc] init];
for(GKTurnBasedMatch* mat in matchList)
{//For every match in the array of matches, find the opponent:
GKTurnBasedParticipant *otherParticipant; //These games only have 2 players. Always.
for(GKTurnBasedParticipant *part in [mat participants])
{ //Loop through both participants in each match
if(NO == [part.playerID isEqualToString:[GKLocalPlayer localPlayer].playerID])
{//If the participant *part is NOT the local player, then he must be the opponent:
otherParticipant = part; //Save the opponent.
}
}
if(otherParticipant != nil && otherParticipant.playerID != nil)
{ //If the opponent exists(like he does)
[GKPlayer loadPlayersForIdentifiers:#[otherParticipant.playerID] withCompletionHandler:^(NSArray *players, NSError *error) {
//Returns an array with only the opponent in it
if([(GKPlayer*)[players objectAtIndex:0] displayName]!=nil)
{//If he has a name:
NSString *nam = [[NSString alloc] initWithString:[(GKPlayer*)[players objectAtIndex:0] displayName]];
//Add the name to the name-array
[playerNames addObject:nam];
}
else
{//If he doesn't have a name, put "No name" into the name array(is not happening)
NSString *nam = [[NSString alloc]initWithString:#"No name"];
[playerNames addObject:nam];
}
}];
}
else
{//If for some reason the entire opponent is nil or he doesn't have a playerID, which isn't happening, add "No name";(This is not happening)
[playerNames addObject:[NSString stringWithFormat:#"No name"]];
}
}
//And THEN reload the data, now with the NSMutableArray 'playerNames' ready and filled with opponent's names.
[[self tableView] reloadData];
}];
This is my CellForRowAtIndexPath:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"matchCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
NSString *name = #"Nobody";
if(playerNames!=nil && [playerNames count]>indexPath.row)
name = [playerNames objectAtIndex:indexPath.row];
[[cell textLabel] setText:[NSString stringWithFormat:#"Game vs. %#", name]];
return cell;
}
The thing is: when the view controller appears: as expected, the tableView is initially empty, but after about half a second, it fills with "Game vs. Nobody" in the correct number of games. If I start two games, and re-enter the view controller, then it's blank at first, and then show "Game vs. Nobody" on two cells. BUT: if I scroll the rows outside the screen, and force them to call for cellForRowAtIndexPath again, then the correct name shows up. So it seems like the [tableView reloadData] in viewDidAppear is called before I ask it to, before the array with names has been filled.
I assume this has something to do with the whole CompletionHandler-thing, as I have never used this before, but I thought everything inside the CompletionHandler was supposed to happen chronologically? Is there something I can call, like onCompletion{} or something?
Ideally, I want an UIAlertView or something to show up with a spinning wheel, the UIActivityIndicationView, and I want it to show until all the data has been loaded correctly. I don't know how to find out WHEN the completionHandler is done, and what it really is..
The playerNames array is being filled within the completion handler for loadPlayersForIdentifiers, which is (I assume) asynchronous. The names array is not populated until the completion handler runs, but you are calling [tableView reloadData] within the other block.
To fix, just move the reload call within the completion block for loadPlayersForIdentifiers (at the end)
I have a simple iPhone app that is parsing data (titles, images etc.) from rss feed and showing in the tableview.
The viewDidLoad has an initial counter value to reach the first page of the feed and load in the tableview by calling the fetchEntriesNew method:
- (void)viewDidLoad
{
[super viewDidLoad];
counter = 1;
[self fetchEntriesNew:counter];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(dataSaved:)
name:#"DataSaved" object:nil];
}
- (void) fetchEntriesNew:(NSInteger )pageNumber
{
channel = [[TheFeedStore sharedStore] fetchWebService:pageNumber withCompletion:^(RSSChannel *obj, NSError *err){
if (!err) {
int currentItemCount = [[channel items] count];
channel = obj;
int newItemCount = [[channel items] count];
NSLog(#"Total Number Of Entries Are: %d", newItemCount);
counter = (newItemCount / 10) + 1;
NSLog(#"New Counter Should Be %d", counter);
int itemDelta = newItemCount - currentItemCount;
if (itemDelta > 0) {
NSMutableArray *rows = [NSMutableArray array];
for (int i = 0; i < itemDelta; i++) {
NSIndexPath *ip = [NSIndexPath indexPathForRow:i inSection:0];
[rows addObject:ip];
}
[[self tableView] insertRowsAtIndexPaths:rows withRowAnimation:UITableViewRowAnimationBottom];
[aiView stopAnimating];
}
}
}];
[[self tableView] reloadData];
}
When the user reaches the bottom of the tableview, i am using the following to reach the next page of the feed and load at the bottom of the first page that was loaded first:
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
float endScrolling = scrollView.contentOffset.y + scrollView.frame.size.height;
if (endScrolling >= scrollView.contentSize.height)
{
NSLog(#"Scroll End Called");
NSLog(#"New Counter NOW is %d", counter);
[self fetchEntriesNew:counter];
}
}
UPDATE2: Here is a more easy to understand description of whats wrong that i am unable to solve: For example there are 10 entries in the each page of the rss feed. The app starts, titles and other labels are loaded immediately and images starts loading lazily and finally gets finished. So far so good. The user scrolls to reach the bottom, reaching the bottom will use the scroll delegate method and the counter gets incremented from 1 to 2 telling the fetchEntriesNew method to reach the second page of the rss feed. The program will start loading the next 10 entries at the bottom of first 10 previously fetched. This can go on and the program will fetch 10 more entries every time the user scrolls and reaches bottom and the new rows will be placed below the previously fetched ones. So far so good.
Now let us say the user is on page 3 currently which has been loaded completely with the images. Since page 3 is loaded completely that means currently there are 30 entries in the tableview. The user now scrolls to the bottom, the counter gets incremented and the tableview begins populating the new rows from page 4 of the rss feed at the bottom of the first 30 entries. Titles get populated quickly thus building the rows and while the images are getting downloaded (not downloaded completely yet), the user quickly moves to the bottom again, instead of loading the 5th page at the bottom of the 4th, it will destroy the 4th ones that is currently in the middle of getting downloaded and starts loading the 4th one again.
What it should do is that it should keep on titles etc from next pages when user reaches the bottom of the tableview regardless of whether the images of the previous pages are in the middle of getting downloaded or not.
There is NO issue with the downloading and persisting data in my project and all the data is persisted between the application runs.
Can someone help to point me out to the right direction. Thanks in advance.
UPDATE 3: Based on #Sergio's answer, this is what i did:
1) Added another call to archiveRootObject [NSKeyedArchiver archiveRootObject:channelCopy toFile:cachePath]; after [channelCopy addItemsFromChannel:obj];
At this point, its not destroying and reloading the same batch again and again, exactly what i wanted. However, it doesn't persist images if i scroll multiple times to reach the next page without the images of the previous page were loaded completely.
2) I am not sure how to use Bool as he explained in the answer. This is what i did: Added #property Bool myBool; in TheFeedStore, synthesised it and set it to NO after newly added archiveRootObject:channelCopy and set it to YES in ListViewController at the very start of fetchEntries method. It didn't work.
3) I also realised the way i am dealing with the whole issue is performance vice not better. Although i don't know how to use images outside the cache and handle them as sort of cache. Are you suggesting to use a separate archiving file for images?
Thanks a lot to all people who have contributed in trying to solve my issue.
Your issue can be understood if you consider this older question of yours and the solution I proposed.
Specifically, the critical bit has to do with the way you are persisting the information (RSS info + images), which is through archiving your whole channel to a file on disk:
[channelCopy addItemsFromChannel:obj];
[NSKeyedArchiver archiveRootObject:channelCopy toFile:pathOfCache];
Now, if you look at fetchEntriesNew:, the first thing that you do there is destroying your current channel. If this happens before the channel has been persisted to disk you enter a sort of endless loop.
I understand you are currently persisting your channel (as per my original suggestion) at the very end of image download.
What you should do is persisting the channel just after the feed has been read and before starting downloading the images (you should of course also persist it at the end of image downloads).
So, if you take this snippet from my old gist:
[connection setCompletionBlock:^(RSSChannel *obj, NSError *err) {
if (!err) {
[channelCopy addItemsFromChannel:obj];
// ADDED
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
dispatch_group_wait(obj.imageDownloadGroup, DISPATCH_TIME_FOREVER);
[NSKeyedArchiver archiveRootObject:channelCopy toFile:cachePath];
});
}
block(channelCopy, err);
what you should do is adding one more archiveRootObject call:
[connection setCompletionBlock:^(RSSChannel *obj, NSError *err) {
if (!err) {
[channelCopy addItemsFromChannel:obj];
[NSKeyedArchiver archiveRootObject:channelCopy toFile:cachePath];
// ADDED
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
dispatch_group_wait(obj.imageDownloadGroup, DISPATCH_TIME_FOREVER);
[NSKeyedArchiver archiveRootObject:channelCopy toFile:cachePath];
});
}
block(channelCopy, err);
This will make things work as long as you do not scroll fast enough so that the channel is destroyed before the feed (without images) is ever read. To fix this you should add a bool to your TheFeedStore class that you set to YES when you call fetchWebService and reset just after executing the newly added archiveRootObject:channelCopy.
This will fix your issues.
Let me also say that from a design/architecture point of view, you have a big issue with the way you manage persistence. Indeed, you have a single file on disk that you write atomically using archiveRootObject. This architecture is intrinsically "risky" from a multi-threading point of view and you should also devise a way to avoid that concurrent accesses to the shared stored have no destructive effects (e.g.: you archive your channel to disk for page 4 at the same time as the images for page 1 have been fully downloaded, hence you try to persist them as well to the same file).
Another approach to image handling would be storing the images outside of your archive file and treat them as a sort of cache. This would fix the concurrency issues and will also get rid of the performance penalty you get from archiving the channel twice for each page (when the feed is first read and later when the images have come in).
Hope this helps.
UPDATE:
At this point, its not destroying and reloading the same batch again and again, exactly what i wanted. However, it doesn't persist images if i scroll multiple times to reach the next page without the images of the previous page were loaded completely.
This is exactly what I meant saying that your architecture (shared archive/concurrent access) would probably lead to problems.
You have several options: use Core Data/sqlite; or, more easily, store each image in its own file. In the latter case, you could do following:
on retrieval, assign to each image a filename (this could be the id of the feed entry or a sequential number or whatever) and store the image data there;
store in the archive both the URL of the image and the filename where it should be stored;
when you need accessing the image, you don't get it from the archived dictionary directly; instead, you get the filename from the it then read the file from disk (if available);
this change would not affect otherwise your current implementation of rss/image retrieval, but only the way you persist the images and you access them when required (I mean, it seems a pretty easy change).
2) I am not sure how to use Bool as he explained in the answer.
add a isDownloading bool to TheFeedStore;
set it to YES in your fetchWebService: method, just before doing [connection start];
set it to NO in the completion block you pass to the connection object (again in fetchWebService:) right after archiving the feed the first time (this you are already doing);
in your scrollViewDidEndDecelerating:, at the very beginning, do:
if ([TheFeedStore sharedStore].isDownloading)
return;
so that you do not refresh the rss feed while a refresh is ongoing.
Let me know if this helps.
NEW UPDATE:
Let me sketch how you could deal with storing images in files.
In your RSSItem class, define:
#property (nonatomic, readonly) UIImage *thumbnail;
#property (nonatomic, strong) NSString *thumbFile;
thumbFile is the the path to the local file hosting the image. Once you have got the image URL (getFirstImageUrl), you can get, e.g., and MD5 hash of it and use this as your local image filename:
NSString* imageURLString = [self getFirstImageUrl:someString];
....
self.thumbFile = [imageURLString MD5String];
(MD5String is a category you can google for).
Then, in downloadThumbnails, you would store the image file locally:
NSMutableData *tempData = [NSData dataWithContentsOfURL:finalUrl];
[tempData writeToFile:[self cachedFileURLFromFileName:self.thumbFile] atomically:YES];
[[NSNotificationCenter defaultCenter] postNotificationName:#"DataSaved" object:nil];
Now, the trick is, when you access the thumbnail property, you read the image from file and return it:
- (UIImage *)thumbnail
{
NSData* d = [NSData dataWithContentsOfURL:[self cachedFileURLFromFileName:self.thumbFile]];
return [[UIImage alloc] initWithData:d];
}
in this snippet, cachedFileURLFromFileName: is defined as:
- (NSURL*)cachedFileURLFromFileName:(NSString*)filename {
NSFileManager *fileManager = [[NSFileManager alloc] init];
NSArray *fileArray = [fileManager URLsForDirectory:NSCachesDirectory inDomains:NSUserDomainMask];
NSURL* cacheURL = (NSURL*)[fileArray lastObject];
if(cacheURL)
{
return [cacheURL URLByAppendingPathComponent:filename];
}
return nil;
}
Of course, thumbFile should be persisted for this to work.
As you see, this approach is pretty "easy" to implement. This is not an optimized solution, just a quick way to make your app work with its current architecture.
For completeness, the MD5String category:
#interface NSString (MD5)
- (NSString *)MD5String;
#end
#implementation NSString (MD5)
- (NSString *)MD5String {
const char *cstr = [self UTF8String];
unsigned char result[16];
CC_MD5(cstr, strlen(cstr), result);
return [NSString stringWithFormat:
#"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
result[0], result[1], result[2], result[3],
result[4], result[5], result[6], result[7],
result[8], result[9], result[10], result[11],
result[12], result[13], result[14], result[15]
];
}
#end
What you are actually trying to do, is implement paging in a UITableView
Now this is very straightforward and the best idea is to implement the paging in your UITableView delegate cellForRowAtIndexPath method, instead of doing this on the UIScrollView scrollViewDidEndDecelerating delegate method.
Here is my implementation of paging and I believe it should work perfectly for you too:
First of all, I have an implementation constants related to the paging:
//paging step size (how many items we get each time)
#define kPageStep 30
//auto paging offset (this means when we reach offset autopaging kicks in, i.e. 10 items before the end of list)
#define kPageBegin 10
The reason I'm doing this is to easily change the paging parameters on my .m file.
Here is how I do paging:
- (UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSUInteger row = [indexPath row];
int section = indexPath.section-1;
while (section>=0) {
row+= [self.tableView numberOfRowsInSection:section];
section--;
}
if (row+kPageBegin>=currentItems && !isLoadingNewItems && currentItems+1<maxItems) {
//begin request
[self LoadMoreItems];
}
......
}
currentItems is an integer that has the number of the tableView datasource current items.
isLoadingNewItems is a boolean that marks if items are being fetched at this moment, so we don't instantiate another request while we are loading the next batch from the server.
maxItems is an integer that indicates when to stop paging, and is an value that I retrieve from our server and set it on my initial request.
You can omit the maxItems check if you don't want to have a limit.
and in my paging loading code I set the isLoadingNewItems flag to true and set it back to false after I retrieve the data from the server.
So in your situation this would look like:
- (UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSUInteger row = [indexPath row];
int section = indexPath.section-1;
while (section>=0) {
row+= [self.tableView numberOfRowsInSection:section];
section--;
}
if (row+kPageBegin>=counter && !isDowloading) {
//begin request
isDowloading = YES;
[self fetchEntriesNew:counter];
}
......
}
Also there is no need to reload your whole table after adding the new rows.
Just use this:
for (int i = 0; i < itemDelta; i++) {
NSIndexPath *ip = [NSIndexPath indexPathForRow:i inSection:0];
[rows addObject:ip];
}
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:rows withRowAnimation:UITableViewRowAnimationBottom];
[self.tableView endUpdates];
A simple BOOL is enough to avoid repetitive calls:
BOOL isDowloading;
When the download is done, set it to NO. When it enters here:
if (endScrolling >= scrollView.contentSize.height)
{
NSLog(#"Scroll End Called");
NSLog(#"New Counter NOW is %d", counter);
[self fetchEntriesNew:counter];
}
put it to YES. Also don't forget to set it to NO when the requests fails.
Edit 1:
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
float endScrolling = scrollView.contentOffset.y + scrollView.frame.size.height;
if (endScrolling >= scrollView.contentSize.height)
{
if(!isDowloading)
{
isDownloading = YES;
NSLog(#"Scroll End Called");
NSLog(#"New Counter NOW is %d", counter);
[self fetchEntriesNew:counter];
}
}
}
And when you finish fetching, just set it to NO again.
I'm loading a TableView from Core Data and it works like a charm. The data contains two fields: Category and Distance. The initial load of the table uses an array with the objects sorted based on Distance. I have a button in the Navigation Bar that I want the user to use to toggle between a Distance-sorted view (the default) and a Category-sorted view. My code for the toggle is:
-(void)toggleView {
NSString *baseItem = #"Proximity View";
NSString *currTitle = self.title;
NSComparisonResult result;
result = [baseItem compare:currTitle];
if (result == 0) {
self.title = NSLocalizedString(#"Category View",#"Categories");
tpData = tpDataCat; //tpDataCat is an array sorted by Category
[self.tblView reloadData];
} else {
self.title = NSLocalizedString(#"Proximity View",#"Distances");
tpData = tpDataDist; //tpDataDist is an array sorted by Distance
[self.tblView reloadData];
}
[baseItem release];
[currTitle release];
}
When I click the toggle button and fire `toggleView, the app just crashes. Any help would be greatly appreciated!!
You shouldn't be releasing baseItem and currTitle.
I would recommend reading the Memory Management Programming Guide; it's an excellent document that can provide background on the appropriate ownership of objects and when releasing would be required.