I made a little program calculating gas consumption.
There is one view controller for each data entry necessary to calculate consumption in the final view controller.
So you enter the driven distance in the first controller, the gas fuelled up in the next controller. in the controller displaying the result, the current date is added, too.
All entries are stored in a plist file as strings for easier use with the tableviews later (except for the date).
Now I want to open this data in a summary view controller to populate a tableview.
Currently I have retrieve 3 arrays from the plist file (similar to the columns of a table):
array 1: NSDate
array 2: NSString representing a number
array 3: NSString representing a number
I know how to populate my tableview, but I cannot wrap my head around the sorting.
I tried changing the column approach into a table row based approach getting every single element from each of the arrays and adding them to a new array, containg each a date and two numbers (as strings).
I tried setting up sortdescriptors, I tried using selectors, but it seems I don't fully comprehend how to work it. Personally, I prefer examples, so I was looking for tutorials on this topic. The developer documentary didn't help that much.
I don't expect to get a complete example for this problem, but maybe some pointers on how to arrange my data and what best to use to sort the complete data array.
Thanks for any pointers or examples.
EDIT:
I finally got all "Table-lines" as "rows" into a dictionary. Now I can access the single columns by key for the column. And this also allows sorting the stringvalues in my array of dictionaries ascending or descending using a sortdescriptor.
This may not be the most elegant approach, but I think I now can do what I wanted.
Excuse the "Table" comparisons, but I find this easier to grasp.
If anyone has pointers to good array tutorials, I'd be more than thankful.
I'm not really clear on how you want to sort, but maybe you can adapt something from this (sorts an array of dictionaries each with a key #"row" with a value type NSNumber) -
First of all, make a comparison result function:
static NSComparisonResult compareRowNumbers(NSDictionary *dict1, NSDictionary *dict2, void * context) {
if ([[dict1 objectForKey:#"row"] intValue] < [[dict2 objectForKey:#"row"] intValue]) {return NSOrderedAscending;}
if ([[dict1 objectForKey:#"row"] intValue] > [[dict2 objectForKey:#"row"] intValue]) {return NSOrderedDescending;}
return NSOrderedSame;
}
Then you can use it like so -
NSMutableArray *myArray = [NSMutableArray array];
// populate your array with loads of stuff (in this case, NSDictionaries as decribed above)
// now sort it
[myArray sortUsingFunction:compareRowNumbers context:NULL];
...and your array is automagically sorted.
Related
I've scoured and still haven't found anything that quite works. Either the question/answer is too old or it simply hasn't worked for me. This is my first attempt at "my own" app. As it seems a right of passage, I'm making a checklist app. Here's what I'm looking for:
My Data Store contains 4 attributes: name, category, isChecked, isActive (more will surely follow as I expand)
When my View Controller initially loads, the NSFetchedResultsController has an NSPredicate that only retrieves the records whose attribute isActive is YES (or [NSNumber numberWithBool:YES). It then takes those records and displays them into the appropriate cells for the user. When a user clicks on a cell, the Data Store updates and changes the isChecked attribute accordingly. Everything works good to this point.
What I need to do now is to be able to remove the items (1 or more) from the list. Specifically, I need it to update the Data Store attributes isChecked and isActive to NO only if it's current isChecked attribute is YES. (I'm not looking to delete the record from the data store as they will be used to build up the database for the users future use.)
I've used, among other things:
[[[self fetchedResultsController] fetchedObjects]
setValue:[NSNumber numberWithBool:NO]
forKey:#"isChecked"];
This does actually work, it removes the checkmark(s) and updates the store accordingly. Problem is, not only am I making another request to the data store for the isActive items, it also searches the entire "Active List" that was fetched and sets each of their isChecked attributes to NO. This may not be too big of an issue for small lists, but as the list(s) expand this can be an issue.
The other problem is, if I add:
[[[self fetchedResultsController] fetchedObjects]
setValue:[NSNumber numberWithBool:NO]
forKey:#"isActive"];
It sets ALL of my list items to NO (as well as a second data store request within the same method.)
So my question is: How can I get through the list, find only the items that are checked and update only those records (set both the isChecked && isActive attributes = NO) whose isChecked attribute is YES rather than working through the entire list?
I've tried creating a separate fetchedResultsController specifically for this buttons action, and it did work (that is to say, it didn't crash) but the debugger popped out a rather large 'Serious Application Error'. I won't post the error message as it's long and most likely irrelevant to any solution.
Any assistance would be greatly appreciated. Thanks in advance and please be gentle :-].
EDIT
I have tried using a for loop, for (NSString *item in fetchedResultsController) but I get the error ...may not respond to 'countByEnumeratingWithState:objects:count'
It seems a loop of sorts is what's needed here, but again, nothing I can find is relevant or it's outdated. Again, thanks for any assistance.
Edit 2
Here is the original error I got when I ran a second separate fetchRequestController for this button/method:
An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (4) must be equal to the number of rows contained in that section before the update (4), plus or minus the number of rows inserted or deleted from that section (0 inserted, 3 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out). with userInfo (null)
You can just loop over the fetchedObjects collection and change the managed objects. After changing them you'll need to reload your list (I guess you use a tableview).
I don't know what your classes are named, but in general you can just loop over the collection of managed objects and change them. Remember that you need to save your managed object context if you want to keep these changes for when the app closes.
NSArray* myCollection = [[self fetchedResultsController] fetchedObjects];
for(ActiveListData *managedObject in myCollection)
{
if(managedObject != nil && managedObject.isChecked)
{
managedObject.isChecked = NO;
managedObject.isActive = NO;
}
}
If you want to do the check on all object in the database you'll need a new method in your NSFetchedResultsController that has a predicate checking on isChecked and then loops over and edits the result collection.
You might want to post your error code as we could be able to point out what you did wrong.
Edit: If you're not familiar with using Core Data the apple documentation provides a lot of information: http://developer.apple.com/library/mac/#documentation/cocoa/Conceptual/CoreData/Articles/cdBasics.html
Thanks to #ggfela for his answer. The processes of his answer were spot on. Here is the actual code I put into my button/method, in hopes of it helping someone else in the future:
NSArray *moc = [[self fetchedResultsController] fetchedObjects];
for (ActiveListData *item in moc) {
if (item != nil && item.isChecked.boolValue == 1) {
item.isChecked = [NSNumber numberWithBool:NO];
item.isActive = [NSNumber numberWithBool:NO];
}
}
// Call to Data Store to update the list
NSError *error;
if (![self.managedObjectContext save:&error]) {
FATAL_CORE_DATA_ERROR(error);
return;
Explanation:
Load the contents of the result from calling the fetchedResultsController method into a temporary variable named moc
Use a for loop to cycle through the array of moc. ActiveListData is the NSManagedObject subclass that I created for my Core Data and is the proper place to insert the separated values/attributes from the data store. From there, it's pretty simple, I ensure that item is not nil AND that the item's attribute is the value I need.
NOTE
Core Data does not store the bool values YES and NO but rather 1 and 0, respectively but when you call or compare the values, you simply can not compare the value of item.isChecked because it is being passed back to you as a bool not as an integer. You can not simply compare item.isChecked == YES either since the #property of isChecked is an NSNumber. So, in the case of the if I put item.isChecked.boolValue as this will give me the representing integer for it's bool value, in this case I have it check for a 1 (YES). (Sorry if my explanation is wrong and/or confusing, but this is how I understand it and is the only way this code works.)
Then, setting the new values of these attributes is like you would expect when setting any other variable. The only "tricky" difference with this is that the NSManagedObject subclass sets the #property of the isChecked and isActive to an NSNumber (as mentioned earlier) so in order to send the proper values back to Core Data you use the method numberWithBool of the NSNumber class.
And just in case anyone gets confused by my FATAL_CORE_DATA_ERROR(error) call this is simply a macro that was defined inside the Prefix.pch file to handle my errors from the managedObjectContext. You can use any (or none) error handling you choose.
Thanks again #ggfela for your help!! If anyone else has any other suggestions on how this code should be applied, then please let me know!
You can use NSBatchUpdateRequest to update multiple records
Examples:
https://www.bignerdranch.com/blog/new-in-core-data-and-ios-8-batch-updating/
http://code.tutsplus.com/tutorials/ios-8-core-data-and-batch-updates--cms-22164
If you wanna see the code Im having problem with, here is the link:
Code
My question is connected with my past question.
I'm really having problem with my NSMutableArray, I'm currently using iCarousel for my slotMachine object(slot1 and slot2). My app works this way:
From PhotoViewController I made a view that has thumbnail images, then assign its frame with button. So if 1 image was pressed, it will save that integer via NSUserDefaults.
Then I will retrieve it in my carouselViewController
Im thinking of adjusting the array but I can't.
I also have tried my question here:
Comparing with NSMutableArray
If only I can do it the same as Array 2 it would be much easy, but still not working.
(ADDITIONAL INFO:)
I have done it this way, have a Viewcontroller that contains the UIImageView with a button in it, so when the user taps it, my CustomPicker pops up. My CustomPicker contains the image on what the user have picked on the camera roll. So each button has a specific value sent to my iCarouselView using NSUserDefaults. carousel1 for First slot and carousel2 for Second slot.
Here is what I wanna do: I want to forcefully make it stop to the index the user picks. (Which Im doing in my carouselDidEndScrollingAnimtaion)
In my carouselDidEndScrollingAnimation method i tested all of my condition(individually) it works perfectly in terms of comparing.
Then when I combine the conditions, the first Two comparison or STOP is RIGHT, but the next two are always wrong. Or sometimes Got mixed up.
I need to scroll the two specific indexes/integer which was User Picked( I already done that) was able to scroll 2 pairs of them but then the next two were always wrong because I think there indexes were adjusting.
PICTURES:
Image Below is my PhotoViewController which contained the Comparing Stage SETTING of my game.UIImageVIew with UIButton.Image that will be put in the number according to it will be Forcefully and should be forcefully shown.
When my iCarousel start then it stops for example in the image below(Which is not the same as the above):
Will be forcefully scroll to the inputted image in the PhotoViewController
Into:
Summary:
Its like this. I have a settingsView from there, I will import my images(Multiple) for Slot1 & Slot2.
Then in another View the PhotoViewController that is where the image above is shown. THe first column corresponds to 1st slot followed by the 2nd slot. if a view is pressed (for example No. 1 of Slot 1 it will load a thumbnail of images loading the images picked from Picker for the Slot 1.
You will have to do it 4 times(pair) ----> The displayed here I get their indexes via NSUserDefaults via button.tag then send to iCarouselView.
Then when you are done (pressed Done button) it will go to iCarouselView then, as shown above thats the view of it.
When pressed it will spin for couple of seconds, then when finished but not stop at the user picked in the PhotoView it will forcefully scroll to that index.
QUESTION:
Is there a way to make my array or my iCarousel.view not adjust their indexes when Im deleting. To still retain my indexes the right way. Or are there other solution like adjusting my array, the same as adjusting my PhotoViewController picked indexes too. Because I think that when my array retain their indexes even deleting I would be able to solve this problem. But still can't.
Hope you understand my question.
Is there a way to make my array or my iCarousel.view not adjust their indexes when Im deleting. To still retain my indexes the right way. Or are there other solution like adjusting my array, the same as adjusting my PhotoViewController picked indexes too. Because I think that when my array retain their indexes even deleting I would be able to solve this problem. But still can't.
The only way you have to modify the way iCarousel manages its indexes is by modifying the code. Indeed, if you look at the removeViewAtIndex method in iCarousel.m, you will see that indexes are managed through an NSDictionary, and at the moment of deleting, the dictionary is rearranged (items are reordered). You could take that method:
- (void)removeViewAtIndex:(NSInteger)index
{
NSMutableDictionary *newItemViews = [NSMutableDictionary dictionaryWithCapacity:[itemViews count] - 1];
for (NSNumber *number in [self indexesForVisibleItems])
{
NSInteger i = [number integerValue];
if (i < index)
{
[newItemViews setObject:[itemViews objectForKey:number] forKey:number];
}
else if (i > index)
{
[newItemViews setObject:[itemViews objectForKey:number] forKey:[NSNumber numberWithInteger:i - 1]];
}
}
self.itemViews = newItemViews;
}
You could apply the same logic to your array, so that the carousel and your array keep in sync. Of course, if you store the indexes somewhere (slot1/slot2/slot2/slot4?), you should also update their values after removing an element.
On the other hand, I think that what you are asking here is how to do something that you believe would solve the problem you have, but you are not really explaining what the problem is. Indeed, if I understand you correctly, what you do is:
spinning the carousel;
when the carousel stops, if it is not by chance on the desired item, you "force" it to scroll to that item.
There is no reason why this should not work after deleting some elements (unless iCarousel has some bugs, then the solution would be catching the bug). The only part is knowing which index is the one you would like to move to.
As a suggestion, I would start off by simplifying your delegate carouselDidEndScrollingAnimation method. Indeed, your carouselDidEndScrollingAnimation has a parameter called carousel, well, I think this is the only carousel you should ever be referring to in that method. If you don't see it, this is the reasoning: each of your carousel will stop scrolling and the carouselDidEndScrollingAnimation will be called; so that method will be called twice. Each time that method is executed you will modify the state of both carousel1 and carousel2 (by calling scrollToItemAtIndex); therefore, on each carousel you will call scrollToItemAtIndex twice.
This does no sound very correct to me. So you should find a way to scroll only carousel1 when carouselDidEndScrollingAnimation is called for carousel1 and to scroll only carousel2 when carouselDidEndScrollingAnimation is called for carousel2.
More generally, another point I would like to raise is that the idea of:
letting a carousel stop;
scrolling it again so that it reaches the desired position;
does not seem the best implementation possible since the user would see the carousel stopping and then starting over again.
The way I would approach this is by modifying directly iCarousel implementation so that it supports this specific behavior you need.
Concretely, give a look at the step method in iCarousel.m. This is called at each frame to produce the carousel animation. Now, in this method there is decelerating branch:
else if (decelerating)
{
CGFloat time = fminf(scrollDuration, currentTime - startTime);
CGFloat acceleration = -startVelocity/scrollDuration;
CGFloat distance = startVelocity * time + 0.5f * acceleration * powf(time, 2.0f);
scrollOffset = startOffset + distance;
[self didScroll];
if (time == (CGFloat)scrollDuration)
{
decelerating = NO;
if ([delegate respondsToSelector:#selector(carouselDidEndDecelerating:)])
{
[delegate carouselDidEndDecelerating:self];
}
if (scrollToItemBoundary || (scrollOffset - [self clampedOffset:scrollOffset]) != 0.0f)
{
if (fabsf(scrollOffset/itemWidth - self.currentItemIndex) < 0.01f)
{
//call scroll to trigger events for legacy support reasons
//even though technically we don't need to scroll at all
[self scrollToItemAtIndex:self.currentItemIndex duration:0.01];
}
else
{
[self scrollToItemAtIndex:self.currentItemIndex animated:YES];
}
}
else
{
CGFloat difference = (CGFloat)self.currentItemIndex - scrollOffset/itemWidth;
if (difference > 0.5)
{
difference = difference - 1.0f;
}
else if (difference < -0.5)
{
difference = 1.0 + difference;
}
toggleTime = currentTime - MAX_TOGGLE_DURATION * fabsf(difference);
toggle = fmaxf(-1.0f, fminf(1.0f, -difference));
}
}
}
and you see that when the carousel stops decelerating, it is scrolled again. This is exactly the same as you are doing, so you might find a way to modify this code and have the carousel scrolls exactly to the index you need. In this way you would get a far smoother spinning of the carousel.
Hope this helps and apologies for the lengthy reply.
Its a little difficult to know what the issue is here. Are you using a single NSMutableArray for the images and using the NSUserDefaults value to get the object at the index in the array?
Im not 100% sure on what is happening. What does the user do(and in what view) and what is triggered after that(which view is presented).
Are you trying to stop the "spinning" images on the image that is the same as the one picked from the previous view?
According to your images above, the images are off by a single index. Is this the case every time? Maybe there is an issue with your fetching from the array.
If you give me some more info I can help.
I looked through the code you pasted again and I think this might be your issue
if (twoSlot1 > [(UIImageView*)[self.carousel2 currentItemView] tag]){
[self.carousel1 scrollToItemAtIndex:(-twoSlot1)-2 duration: 3.5f];
} else {
[self.carousel1 scrollToItemAtIndex:-twoSlot1 duration: 3.5f];
}
On all other code blocks like that you have this where you call each carousel. In the above code you call carousel 1 twice.
if (slot2 > [(UIImageView*)[self.carousel1 currentItemView] tag]){
[self.carousel1 scrollToItemAtIndex:(-slot2)-2 duration: 3.0f];
} else {
[self.carousel1 scrollToItemAtIndex:-slot2 duration: 3.0f];
}
if (twoSlot2 > [(UIImageView*)[self.carousel2 currentItemView] tag]){
[self.carousel2 scrollToItemAtIndex:(-twoSlot2)-2 duration: 3.5f];
} else {
[self.carousel2 scrollToItemAtIndex:-twoSlot2 duration: 3.5f];
}
You call self.carousel1 when you should be calling number 2.
Is this correct?
Referring to your question. You want an array that does not change its members' indexes when a member is deleted from the array.
I guess you could use an NSMutableDictionary. It is an associative array so to say, where the indexes are of your choice and they remain unchanged when you delete a member from in between.
You may still use 0..n as your Index. You can still use some methods that you are familiar with from NSArray, such as count. You can use an enumerator to go through all members of the dictionary. On the other hand you can still use your for-loops as you are used to use them with arrays. Just be prepared that a) objectForKey:i may return nil if the key/index does not exist (e.g. was deleted) and that count retuns the number of the objects but not the highest index+1 as it does with arrays.
Not sure if I understand completely, but when one of the elements in your mutable array is deleted, rather than just deleting it, maybe insert it with another "dummy" place holder object? That way your indexes won't change at all when a delete occurs
I'm having a hard time understanding your overall problem, but from what I can gather the crux of your question is this:
Is there a way to make my array or my iCarousel.view not adjust their indexes when Im deleting.
I don't know whether it will solve your bigger issue, but using an NSMutableDictionary to simulate an array should allow you to do this. You can simply use the indices as the keys to the dictionary, and then when you remove the item associated with an index, no other indices will be adjusted as a result. For example:
NSMutableDictionary *arrayDict = [[NSMutableDictionary alloc] init];
[arrayDict setValue:foo forKey:[NSNumber numberWithInt:[arrayDict count]]];
[arrayDict setValue:bar forKey:[NSNumber numberWithInt:[arrayDict count]]];
[arrayDict setValue:fooBar forKey:[NSNumber numberWithInt:[arrayDict count]]];
And then you can access the object an at index with [arrayDict objectForKey:[NSNumber numberWithInt:index]].
Note that using an NSNumber for the key parameter of setValue:forKey: will generate a warning, but you can safely ignore this (or use the string representation if it bothers you).
I'm parsing data from a remote database to an iphone application and populating the table view. The program is able to populate the table view fine however its all the records. To sort the records i was advised to use NSPredicate to sort the data (which works) but when it tries to load the data, the program exists with no warnings in the console. I dont understand why, could someone have a quick glance over the code and tell me where im going wrong? (i think its something to do with these lines return [rows count]; and NSDictionary *dict = [rows objectAtIndex: indexPath.row];). Thanks for any help on this ...
In your viewDidLoad, retain the array and try.
rows = [[courses filteredArrayUsingPredicate:predicate] retain];
You should retain the rows array since filteredArrayUsingPredicate should return an autorelease object.
Is it possible to display information in TableView as given in screenshot?
Here: 'MyFund' is sum of amounts of Rob, Mike and Sam Fund.
I am not sure how will I sum up the amounts and display in Table headers.
Please help!
Hmm. I suppose you could calculate the summation in sectionIndexTitlesForTableView as such:
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
// replace the following with however you'll calculate the sums
int sumSectionOne = 4;
int sumSectionTwo = 3;
return [NSArray arrayWithObjects:[NSString stringWithFormat:#"$%d",sumSectionOne], [NSString stringWithFormat:#"$%d",sumSectionTwo], nil];
}
but it does mean you'll be invoking reloadSections a lot on that table view. Moreover, this isn't entirely the intended purpose of UITableView (though admittedly a really easy way of doing this).
There is no sort cut for this you need to implement a good store data structre then a logic to fetch them.so its all about logic,see my approach.
You need to add this record in an array with dictionary form,means add fund with money in a dictionary with two different key says "fund" and "money"(any thing).
when you make section means in titleForHeaderInSection method, you need to implement the logic.you need to make loop upto array count and access the dictionaries and add all "money" values.
Now you need to implement.if you have face any problem in code then again ask.
Is it possible to detect the last item when using NSFastEnumeration?
for(NSString *str in someArray){
//Can I detect if I'm up to the last string?
}
Is it possible to detect the last item
when using NSFastEnumeration?
Not with 100% accuracy (or by limiting the array contents to being entirely unique pointers so that pointer comparison works as discussed in another question) without also doing a bunch of work that leads to just doing it the old way.
Note that if you can target 4.0+, you can use enumerateWithBlock: that gives both the item and the index. It is as fast or faster than fast enumeration, even.
I think the only way is the old fashioned way, something like:
NSUInteger count = [someArray count];
for (NSString *str in someArray) {
if (--count==0) {
//this is the last element
}
}
At the end of the loop, "str" will still be pointing to the last element. What is it you need to do?