I am having trouble grasping the concept of multi component uipickerviews. I really would like to just OWN this subject. I would like to make a 4 component pickerview with components that are dependent on one another.
The first component is being populated from an array from my db, and that is showing up fine. I have all of the other info available in arrays, but I am just getting hung up on the dependent aspect of my pickerview. I figure the best way to make component 2's data depend on comp 1 is to link them somehow within the didSelectRow section. But I don't know the syntax.
I have been working at this for hours now and feel like I am really close, but I just need some help with a few issues. What is the syntax for connecting components so they depend on each other? Something like this? (Which is awful I know, but I am thinking that is the direction I need to get) :
if(picker = pickerComponent1)
//set number of rows for comp2 and also the content etc...
Another issue is determining the numberOfRowsInComponent bit because they aren't in the same method...
If anyone knows about (or wants to give :) a tutorial on this subject, it would be so helpful! Or if you are knowledgeable on the topic and would like to share some of what you know, that would be perfect too. I would really like to see this seemingly simple task completed.
It's quite simple. In the pickerView:didSelectRow:inComponent: method, just call [myPicker reloadComponent:] for all components coming after the one where the selection changed. The picker will then automatically ask its datasource (your view controller, presumably) for the number of rows and the rows' values.
Then, in pickerView:numberOfRowsInComponent: and pickerView:titleForRow:forComponent:, return the appropriate values (the count and contents of the corresponding array) depending on the values of the parent components' selected rows.
Related
How can I make my Crystal Report look like the attached image? I have had no success creating it with a crosstab.
The short answer is that Crystal Reports isn't really equipped to handle the format you're dealing with. And here's why:
Let's assume for a moment you've already figured out how to interpret your query into something usable. Since we aren't using a Cross Table, the best you could hope for would be setting a Details section for each individual time slot and arranging a large number of formulas into a grid shape:
The problem is that every Formula would need to be unique; interpreting whether there is a Class at that Time and Date, and which Class it is. There would be up to 168 of those formulas and you'd have to manually go in and modify each one to check for their own unique combination of Date and Time. Which defeats the whole purpose of using a computer - to make repeated tasks easier.
Plus you'll have difficulty with the formatting: You'd need to program every "cell" to use a unique set of colors based on the displayed Class. That part is technically doable, but there's no way to "merge the cells" when classes last longer than a half hour. You'd end up with something like this:
So don't torture yourself trying to make this happen in Crystal. Even with all the time and effort it would take to formulate the grid, there's no good way to make it look like your screenshot.
That said, it looks as though you managed to put a schedule together in Excel. Is there any reason you can't use Excel instead? It's a much more powerful tool, and a cursory Google search suggests it can handle queries as well.
Is there a way to dynamically declare a certain number of UIButtons based on the number of iterations in a for loop?
the actual number would be passed in from the user or based on an array length
so pseudo-code would be
for num in total{
//declare a UIbutton with a unique name
}
If you are using UITableView the best way to accomplish this is using the table own behavior to populate its cells automatically with your source date (array, dictionaries, etc) even with data gathered from external sources like a REST service.
The way to do this is creating a custom cell with each outlet and point them to your sources.
After some googling, I think this is called metaprogramming and that swift doesn't have it yet :(
edit: looks like i was way overthinking things. this is actually fairly straightforward if i think about it without looping
Right, so my UITableView loads and puts all the cells in Alphabetical order. Information is then downloaded from a server and calculations are done, with the TableView being reloaded once everything is complete. Currently this is quite a simple procedure as once the information is downloaded from the server, the cells don't even move, they are left in their alphabetical order. Nothing really happens other than half of the information is filled in and small changes are made depending on the calculations. I was wondering if there was an easy way of putting the cells into sections depending on the calculations done after the download is complete? I did have an idea of creating 4 arrays (there will only be 4 sections ever) and once isLoading is set to no, changing the data source of the TableView to have sections, however, that sounds a bit... iffy. I know this is a theoretical question as opposed to a coding problem, but before I go and mess up my code, in what is sure to be a stupidly inefficient way of doing things, is there an easy way of "assigning" UITableViewCells to sections?
My main issue with my way of doing it is that should the user delete a cell, deleting the appropriate entry in Core Data will be a little tricky and prone to errors. This lead me on to another idea. What if I added an extra attribute to my Core Data entity. That attribute would be assigned and then saved once the calculations were done. The problem with this is that no existing databases would work. There has to be a neat way of achieving this.
Thanks for the help. If you need me to post any code just say so and I will.
You should be fine if you implement the data source methods related to sections.
For example:
numberOfSectionsInTableView
sectionIndexTitlesForTableView.
Any time the table data is reloaded (e.g., [self.tableView reloadData]), these methods will be called and the data will be placed into their sections.
Keep in mind that the cells are just the visual representation of your model, which in this case is your fetched data. The cells are not assigned to sections; they are simply created however you specify for your model (via the table view data source and delegate methods).
Regarding deletion of entries while using Core Data, I suggest taking a look at NSFetchedResultsController. The latter will monitor any changes to your table's data and message its delegate, your table view controller, when updates are made.
For example, a deletion would start with a call to the table view delegate like normal (i.e., via tableView:didEndEditingRowAtIndexPath). Within the latter, you would then delete the entry from core data (e.g., [self.myDatabase.managedObjectContext deleteObject:entity]). Assuming you initiated the NSFetchedResultsController w/ the same managed object context, the deletion would be automatically reflected back to your user.
If you're using a remote DB, however, you'll also have to perform a save (however you've implemented that) to ensure the DB is updated too.
Note also that if you use an NSFetchedResultsController, you don't need to implement the section data source methods since NSFetchedResultsController can handle that for you. Just define the key-path in your data model that will return the section name when initializing the NSFetchedResultsController.
This question is about handling arrays of information, there's are many ways I could do this, but I would like some input from programmers with more experience, I know what I want to do just not how to organize the information the best way, and objective-C is really making me ponder this, I don't want to get 100 hours into work a decide, oops this wasted the beast way to do this. So here goes:
I have a grid where I'm simulating a playing field, each piece of the grid I call a cell. The cells have around 20 different values each, all integers, nothing fancy. A change to a cell will be either by player input, or occur or by surrounding cells through different algorithms.
The changes to cells will occur once a turn is complete, so it's not real time. Now, I'm not even sure about doing this with a MutableArrays, a plain Array, or just a plain matrix. Arrays are good at keeping such info for one dimension, but I would imagine would become quite cumbersome if you have to address a batch of 10,000 of these cells. On the other hand a simple matrix might not be so elegant, but probably easier to work with.
Any insight would be greatly appreciated.
You have two options here that I see:
1) Use standard containers
Assuming that the playing field is of constant size, then you can create a mutable array of x*y size, and populate it with mutable dictionaries. By giving everything in the second mutable dictionary keys, you can query and set their properties (all objects of course, so wrap ints in NSNumbers etc). For indexing use a macro INDEX_FROM_ROW_COL(row, col) and apply the appropriate code to multiply/add.
2) Create a helper object subclassed from NSObject. It would manage mutable objects as above, but you could load it with functionality specific to your application. You could provide methods that have parameters of "row:" and "col:". Methods that change or set properties of each cell based on some criteria. Personally, I think this is a better idea as you can incapsulate logic here and make the interface to it more high level. It will make it easier to log whats going on too.
Normally to use UITableView, the number of sections and rows per section are known. But what if they aren't? I want to implement a lazy search, so that I actually search for the next match when new data needs to be displayed. Something on the lines of: db.prepareSearch(query) and then call something like db.nextSearchResult() when it is time to display a new cell. The search result determines if a new section is required or not (search results are inherently sorted).
Not sure why it wasn't done this way to begin with, so that it asks for a section until no more are available or needed, and for cells in the section until no more are available or needed, instead of having to specify the totals, which implies having to finish the whole search before starting to display the first few results.
To get the number of sections and rows, it's easy -- ask your data source. If your data source has no way of telling you this, make a way.
For instance, if you have to query a table and ask how many rows there are for your sections, do that. Then, for each section, ask how many rows there are which match that section.
What it also sounds like is you want to paginate your data. Meaning when you get to a certain point, have a "load more data" cell or some-such. This is fine too, just add a sentinel node to your data source, and whenever that particular item comes up, display your alternate cell while you load your data, then remove it after your next data is fetched. I do this in a few of my apps.
If I'm understanding this correctly, at the point of drawing/populating, you will know how many rows/sections you have.
If your changing the underlying data using db.nextSearchResult() then you must be calling [tableView reloadData] to trigger a UI update, at this point you should know how many sections and rows you have.
I have to admit I'm a little confused to the exact issue here.