I'm writing a simple iPhone app which lets a user access a series of calculators. It consists of the following:
UITableViewController (RootViewController), with the list of calculators.
UIViewController + UIScrollView (UniversalScroller), which represents an empty scroll view - and has a 'displayedViewController' property.
UIViewController (Calculators 1-9), each of which contains a view with controls that represents a particular calculator. Each calculator takes 3-5 values via UITextFields and UISliders, and has a 'calculate' button. They can potentially be taller than 460px(iPhone screen height).
The idea is:
User taps on a particular menu item in the RootViewController. This loads and inits UniversalScroller, ALSO loads and inits the UIViewcontroller for the particular calculator that was selected, sets the displayedViewController property of UniversalScroller to the newly loaded calculator UIViewcontroller, and pushes the UniversalScroller to the front.
When the UniversalScroller hits its 'viewDidLoad' event, it sets its contentSize to the view frame size of its 'displayedViewController' object. It then adds the displayedViewController's view as a subview to itself, and sets its own title to equal that of the displayedViewController. It now displays the calculator, along with the correct title, in a scrollable form.
Conceptually (and currently; this stuff has all been implemented already), this works great - I can design the calculators how I see fit, as tall as they end up being, and they will automatically be accommodated and displayed in an appropriately configured UIScrollView. However, there is one problem:
The main reason I wanted to display things in a UIScrollView was so that, when the on-screen-keyboard appeared, I could shift the view up to focus on the control that is currently being edited. To do this, I need access to the UniversalScroller object that is holding the current calculator's view. On the beganEditing: event of each control, I intended to use the [UniversalScroller.view scrollRectToVisible: animated:] method to move focus to the correct control. However, I am having trouble accessing the UniversalScroller. I tried assigning a reference to it as a property of each calculator UIViewController, but did't seem to have much luck. I've read about using Delegates but have had trouble working out exactly how they work.
I'm looking for one of three things:
Some explanation of how I can access the methods of a UIScrollView from a UIViewController whose view is contained within it.
or
Confirmation of my suspicions that making users scroll on a data entry form is bad, and I should just abandon scrollviews altogether and move the view up and down to the relevant position when the keyboard appears, then back when it disappears.
or
Some pointers on how I could go about redesigning the calculators (which are basically simple data entry forms using labels, sliders and textfields) to be contained within UITableViewCells (presumably in a UITableView, which I understand is a scrollview deep down) - I read a post on SO saying that that's a more pleasing way to make a data entry form, but I couldn't find any examples of that online. Screenshots would be nice. Anything to make my app more usable and naturally 'iPhone-like', since shuffling labels and textboxes around makes me feel like I am building a winforms app!
I've only recently started with this platform and language, and despite being largely an Apple skeptic I definitely see the beauty in the way that it works. Help me solve this problem and I might fall in love completely.
Dan
If you have the particular calculator view, you should be able to get to the scroll view via the superview property (though there might be more than one intermediate view, so you might need the superview of the superview).
Related
I am new-ish to iphone development and I am trying to figure out how I can fix a view after it has reached a the top of the screen when a user scrolls a window. Then the view would unlock when the window is scrolled down again to go back to its original position. Ive seen this on on a few apps like instagram (with the user name separators).
Does this design pattern have a specific name?
An example (not iPhone though) can be seen on http://mashable.com/ -- Look at "The New Stuff", "The Next Big Thing", and "What's Hot" bar. See how it locks as you scroll down
My solution for you is
create a UITableView
create a UIView separately which will be used as fixed table header
setup the table's tableHeaderView property to conform the UIView's frame
as UITableView is inherited from UIScrollView you can rely on scrollViewDidScroll method in which I properly adjust my fixed header as Y coordinate changes when scrolling the table.
There can be other similar solution for this too but a strenght of this particular solution is that you can manipulate the fixed header's gui element throughout the scrolling easily.
An example is always better than writing down the details so I created for you (and hopefully for others here at SO) a sample project (of course quick'n dirty), which you can find here at github:
https://github.com/codedad/SO_Fixed_TableHeader_iOS
If I'm correct, you're trying to achieve something like the UITableView in the Contacts app?
It uses the sections of the UITableView for the sorted letters and displays them always on top.
Have a look a this question and create custom section headers.
I'm new to iOS development and am trying to build something like the screen below:
If I was doing it in Android, I can easily build the above UI in a few minutes. However, I don't know how to go about it with iOS.
I understand that the whole ViewController can be embedded in a navigation controller, which produces the title bar above. What about the bottom part though? I'm thinking of using something like a grouped UITableView but I'm not sure, since every cell will have very different contents:
A search bar, perhaps a subclassed UISearchBar, which I also don't know how to customize--the Search button at the right is required but isn't in the default UISearchBar. When the user taps on it, the UISearchBar must be translated to the navigation bar, no need to display a UITableView of suggested results. I don't know how to do that, too.
A button that, when tapped, flies in a modal from the bottom (I imagine it to be another ViewController with a grouped UITableView), to allow the user to choose from defined locations. Once selected, the modal closes and the button text is replaced with the selected location. This sounds much easier to do.
A header ("Item categories") and the list of categories, which may change in number. If the parent isn't a grouped UITableView, I think this part can be a UILabel and a non-scrolling UITableView with a height that changes depending on how many cells it has. If there are plenty table cells that don't fit given the screen's height, everything below the navigation bar can be scrolled vertically. That, I also don't know how to do.
If anyone can just guide me to what native iOS components I can use to build the above screen, and maybe a couple of tutorials to the things I just said I don't know how to do, I'd appreciate it.
You said it right .All the basic info you need is with you.
To build a searchbar like that i dont think you have to subclass it.
Bottom comprises of tableview.
Actually these Questions are seperately available in SO itself.So search seperately for your needs and you can achieve whatever you want
One basic principle : You cant achive anything by just thinking.Trying and get to it and if you have any issues look forward at it.All the issues will have an answer on the way.
Lots of components you need there.. Search Bar, UIPickerView and UITableView. I would like to give you some pointers.
1) You can refer http://www.appcoda.com/how-to-add-search-bar-uitableview/ for Search bar
2) When clicking on the Button, you can bring up a UIPickerView instead of another controller. For that you can refer http://www.techotopia.com/index.php/An_iOS_5_iPhone_UIPickerView_Example
3) You can use a normal Tableview with a single section, configure the section header to display Item categories.
You are asking too much to ask how to do every component of your UI. I will just answer a little.
Yes, a grouped table view is a good design. I am using a grouped table view for varying types of input. I have an actual table, with rows that can be added, and deleted, and contain an editable text area. Then I have three groups that only really show one piece of content each: two are sliders and one is a switch.
For choosing the location, pushing another view controller on your navigation stack would be the more typical way to handle it. You will save some effort that way, with some buttons and behaviors built in, but a modal view controller is not much harder. I'm not sure if you can make a navigation view fly in vertically, but does your app have to be frame-for-frame identical to the android version?
I've understood that I need to subclass a UIView t be able to draw inside it.
The thing I don't understand yet, is the philosophy of the way i must be done...
Let's say I have a view controller, and depending on context, I may want to draw a line into one of the subviews it manages, or a circle, or a rect, or a processed graphic. Or lets say two points that are moving inside a view into a defined rect and that display a bigger point when they are close.
How may I subclass and define the subview to make it able to do this only into its drawRect method ?
How does the controller, that manages more than this simple UIView (let's imagine you have a view controller that manages a view inside which there are many other view, and you want to make some drawings in two of them), and that knows what is needed to be drawn into the correct view (it's a controller, isn't it ?), may interact with the views ? And when the drawing is done, how may the views interact with the controller ?
I've read many doc about drawings (apple, web, forums, tutorials, ...), but I still can't touch the philosophy of the way this must be done.
it's very simple. Make a new class, OliverView, which is a UIView. (ie, it is a subclass of UIView.) In that view, make it draw stuff in a fancy way, inside drawRect.
Now make a UIViewController, called OliverVC. In storyboard put an OliverView inside OliverVC. (beginner explanation of how to do that).
In the OliverView, have properties "hours", "minutes", "seconds".
Now, in OliverView - in the drawRect - have a fancy way to display those values. (Pie chart, glowing letters, animation - whatever you want.)
Now, up in OliverVC, do some calculations to determine the time in Zimbabwe, for example.
Once you want a time displayed, simply set those properties in OliverView - - and you are done.
Your colleague could be programming the OliverView. You need know nothing about how she is going to display the time. Conversely, your colleague need know nothing about your calculations in OliverVC..
So, it's simpleL One part has the job of displaying the data. One part has the job of coming up with the data (doing whatever sort of calculation is relevant in the app).
It's the only architecture possible in a "real time" screen device where the views can and do change at any time.
In answer to your question below: you've forgotten that quite simply, if you have a button that would be a whole separate element. (Perhaps sitting "on top of" the OliverView.) So, it's easy!
The -drawRect method in your UIView subclass defines the onscreen appearance of the view. All drawing is done in -drawRect. Your UIViewController calls methods on its UIView to tell it to draw something differently or to perform some other action.
The UIViewController manages everything to do with the view that is not inherently associated with the drawing of the content. Data associated with the view is often stored in the controller.
I have written a little PDF viewer which is supposed to show PDFs page by page to reduce memory usage.
It consists of a PdfViewController which shows a specific page of the PDF (using UIScrollView, CATiledLayer).
Now the (maybe stupid) question is: if I want to show the next page (using a swipe gesture ot whatever), how would I do that? Should my controller handle it and update its views (which is a horror becaue CATiledLayer seems to crash as soon as you look at it :-)), or should there be an "outer" controller which generates a new PdfViewController for every page flip (the more flexible aproach)?
What is the best practice in these situations? Looking at UINavigationController, you're supposed to push a new UIViewController for every level. But there, all controllers being pushed may be different. In my case, all pages are using the same controller.
You likely shouldn't use the UINavigationController for that. In general, the UINavController should be used for drill-down operations, where you have a limited set of items to be pushed.
In your case, I think the best option is to use a large UIScrollView which will take care of the pagination and then just create a new UIView with the CATiledlayer inside.
I created for my app Quicklytics a PagedViewController class that does most of that for you. You basically create a PageDataSource that creates the UIViews for each page, and handle it over to the control. You may not use this exactly as is on your code, but it'll give you a good idea on where to go:
https://github.com/escoz/monotouch-controls/blob/master/UICatalog/PagedViewController.cs
Hope this helps you.
Here are two useful resources
Fast and Lean PDF Viewer for iPhone / iPad / iOs - tips and hints? collects a whole lot of information on displaying pdfs.
https://github.com/vfr/Reader a basic pdf reader for ios that does what you are trying to do.
In terms of whether to use nested UIViewControllers I would recommend against it, however if you do you should be aware that they will not handle rotation very well (I don't think they receive orientation change events) as well as viewDidAppear and other view lifecycle events, also make sure only to display modal view controllers from the root view controller otherwise they won't show properly (I had issues with them appearing in the wrong orientation in landscape, or in the wrong position).
In the app I built I used one UIViewController to manage the display of the pdf and I subclassed NSObject for any other "sub" controllers to make it more manageable. For example I had vertical scrolling as well as horizontal scrolling of pdf pages. My first attempt used nested UIViewControllers however I had issues with orientation till I rebuilt using controllers subclassed from NSObject for managing vertical slides.
I have been facing the same nested UIScrollView problem for long time.I tried some open source codes like Scrolling madness ,three-20 and others but all fails finaly.I am trying to make a photo Viewer application same as iPhone.For that I have created the structure like this:-
1)one View controller.
2)on view of view controller one UIScrollView (i.e inner/parent scroll view) as a child.
3)on inner/parent scroll view number of child scroll views(i.e. outer/child scroll views) ,each represents one page of photos application.
4)On each scroll view one image View on which i am displaying my image.
So what I want is when user scrolls the outer scroll view it should scroll horizontally with all the child views so I will get the look and feel of paging in photos application.Also when user is on one specific image(i.e. child/outer scroll view) he should be able to zoom in/out,swipes and perform single/double tapping.I was able to make it work in sdk 2.1,but it dosnt work since sdk 3.0.Please tell me the idea behind your project.Means which scroll view you are subclassing ,in which view to detect touches.How this completely child - parent relation should be.
If possible provide any sample code also.
There is a WWDC session from 2010 that deals with this very issue.
Here's the short of it:
You need a single scroll view that is paginated and scrolls horizontally. Each "page" of that scroll view is another scroll view containing a photo.
First, it looks like you want to subclass UIScrollView? Every interaction method you need is provided for you in either the delegate callbacks or the touch methods. (Many of Apple's more advanced classes, such as UIScrollView, react poorly to subclassing.)
Second, it sounds like you have a first responder problem. IOW, your innermost scrollview isn't getting the first crack at the touch events.
Andrew
I also struggled with this for a long time trying samples you mentioned. I could finally figure it out with the samples provided by apple (iphone dev center).
http://developer.apple.com/iphone/library/samplecode/Scrolling/Introduction/Intro.html
http://developer.apple.com/iphone/library/samplecode/ScrollViewSuite/Introduction/Intro.html
The first one is pretty basic and probably what u already have. The second one is all about zooming, etc. Just study these and the samples you already have, I think you will be able to figure it out. On specific topics just come back here search for answers or post another question.
EDIT: I forgot this one check out these examples by Andrey Tarantsov hosted on github. This is what you want... http://github.com/andreyvit/ScrollingMadness