I'm implementing a document viewer with highlighting/annotation capabilities for a custom document format on iPad. The documents are kind of long (100 to 200 pages, if printed on paper) and I've had a hard time finding the right approach. Here are the requirments:
1) Basic rich-text styling: control of left/right margins. Control of font name, size, foreground/background color, and line spacing. Bold, italics, underline, etc.
2) Selection and highlighting of arbitrary text regions (not limited to paragraph boundaries, like in Safari/UIWebView).
3) Customization of the Cut/Copy/Paste popup (UIMenuController) This is one of the essential requirements of the app.
My first implementation was based on UIWebView. I just rendered the document as HTML with CSS for text styling. But I couldn't get the kind of text selection behavior I wanted (across paragraph boundaries) and the UIMenuController can't be customized from within UIWebView.
So I started working on a javascript approach, faking the device text-selection behavior using JQuery to trap touch events and dynamically modifying the DOM to change the background color of selected regions of text. I built a fake UIMenuController control as a hidden DIV, positioning it and unhiding it whenever there was an active selection region.
Not too shabby.
The main problem is that it's SLOOOOOOOW. Scrolling through the document is nice and quick, but dynamically changing the DOM is not very snappy. Plus, I couldn't figure out how to recreate the magnifier loupe, so my fake text-selection GUI doesn't look quite the same as the native implementation. Also, I haven't yet implemented the communication bridge between the javascript layer and the objective-c layer (where the rest of the app lives), but it was shaping up to be a huge hassle.
So I've been looking at CoreText, but there are precious few examples on the web. I spent a little time with this simple little demo:
http://github.com/jonasschnelli/I7CoreTextExample/
It shows how to use CoreText to draw an NSAttributedText string into a UIView. But it has its own problems: It doesn't implement text-selection behavior, and it doesn't present a UIMenuController, so I don't have any idea how to make that happen. And, more importantly, it tries to draw the entire document all at once, with significant performance degradations for long documents. My documents can have thousands of paragraphs, and less than 1% of the document is ever on screen at a time.
On the plus side, these documents already contain precise formatting information. I know the exact page-position of every line of text, so I don't need a layout engine.
Does anyone know how to implement this sort of view using CoreText? I understand that a full-fledged implementation is overkill for a question like this, but I'm looking for a good CoreText example with a few basic requirements:
1) Precise layout & formatting control (using the formatting metrics and text styles I've already calculated).
2) Arbitrary selection of text.
3) Customization of the UIMenuController.
4) Efficient recycling of resources for off-screen objects.
I'd be happy to implement my own recycling when text elements scroll off-screen, but wouldn't that require re-implementing UIScrollView?
I'm brand-new to iPhone development, and still getting used to Objective-C, but I've been working in other languages (Java, C#, flex/actionscript, etc) for more than ten years, so I feel confident in my ability to get the work done, if only I had a better feel for the iPhone SDK and the common coding patterns for stuff like this. Is it just me, or does the SDK documentation really suck?
Anyhow, thanks for your help!
Does your document have any semantic components other than each paragraph? If you already have some concept of sections or pages, I would recommend you render each one of those as an independent tablecell. It's pretty simple to create a tablecell that makes you forget you're actually looking at a UITableView. All you would need to do is override drawRect: and setSelected: and setHighlighted: and tah dah! No More cell dividers unless you want them. Furthermore you could do some nifty things by using a tableview as your base. If you defined sections in the UITableView then you could have a nifty header that scrolls along as you're paging through your document. Another thing you could do is add a "jump to section" bar / a bookmarks menu, and that way you don't have to provide selection across the boundaries of sections.
Massive copy paste blocks would be pretty painful on the system as well. Further, if you went through the trouble to provide this content you might not want to make it too easy for someone to copy it all at once... (Can't follow this line of thought more without more specifics on your project).
If you really do want to provide the copy paste options you could add buttons to each logical page or section that immediately selects and copies the whole section for the user's convenience. (Maybe with citation associated?)
I recommend you lookup the UITableViewCell UITableViewDelegate and UITableViewDataSource in the SDK docs as those pages will significantly help if you choose to use this suggestion.
Just two random observations:
Can you afford to create a paging interface? (As opposed to “endless scrolling”.) It looks like a paging interface would be a lot easier on system resources.
The UIActionBar is actually the UIMenuController class. The interface is a bit weird, as the menu is a singleton (wtf?), but I’m sure you’ll have no trouble figuring it out.
Hope that helps.
Here's a potential solution, but I don't know if it's crazy. Since I'm still so new to iPhone development, this might be a big no-no.
Anyhow, I had the idea to render each paragraph of the document (whose dimensions I've already precisely calculated) as a cell in a UITableView. Since UITableView already has mechanisms for cell recycling, I wouldn't have to implement that from scratch, and the document could be arbitrarily long without causing resource consumption problems.
Of course, I'd want to get rid of the line separators between cells, since I want the UI to look like a document instead of a table.
Or maybe I could render each page of the document (like a typical PDF, this is a paged-document format) as a table cell, and override the cell-separator graphic to look like a page boundary...
But would it be possible to get rid of the default touch behavior within the table, and instead implement text-selection on the table cell contents? Would it be completely impossible to implement text selection that crosses paragraph boundaries (between multiple table cells)?
The UIWebView is a good choise, but we need another application to pre render the pages percisely using each font and each style sheet and store the rendring information into a database table:
chapter_id int primary key,
startlocation int,
end location int,
fontsize int (or stylesheetname string)
Using JavaScript we can calculate how many words fit in a div with out scrolling.
UIWebView is good as it provide rich content and it has selection and highlighting behavior.
Hope this helps.
Related
I am very new to iphone application development and am struggling to create a table view page where each row contains a left-aligned label with an editable text next to it - just like how it works in the email account details page in the settings application on my iphone.
I have been googling the subject for hours and it is now somehow clear to me that I need to add UITextFields to UITableViewCells, but it is still not at all clear to me how I make these text fields take up the right amount of space:
How do I make the text fields align above each other?
How do I make the text fields expand as far as possible to the right?
How do I prevent the text fields from hiding part of the left-aligned label?
Read the Apple Docs on Tableviews there are a number of predefined table cells. Also look at the Tableview programming Guide. Pick the one that has the font characteristics that you want and Apple will take care of it for you. Also, in the Settings app, the settings are a Grouped style.
For the look you are describing I think it is called UITableViewCellStyleSubtitle.
You need custom UITableViewCells and there are a number of ways of making them. For your purposes, any one of the techniques detailed in the Apple documentation will probably suffice.
An alternative to those approaches is in GSUtils (full disclosure: open-source library written by me), where you can use the same approach to designing your table view cells as you would design a UIView.
I have a problem. Part of my app requires text to be shown in a table. The text needs to be selectable/copyable (but not editable) and any URLs within the text need to be highlighted and and when tapped allow me to take that URL and open my embedded browser.
I have seen a couple of solutions that solve one of either of these problems, but not both.
Solution 1: Icon Factory's IFTweetLabel
The first solution I tried was to use the IFTweetLabel class made possible by Icon Factory and used in Twitterrific.
While this solution allows for links (or anything you can find with a regex) to be detected to be handled on a case by case basis, it doesn't allow for selecting and copying.
There is also an issue where if a URL is long enough to be wrapped, the button that the class overlays above the URL to make it interactive cannot wrap and draws off screen, looking very odd.
Solution 2: Use IFTweetLabel and handle copy manually
The second thing I tried was to keep IFTweetLabel in place to handle the links, but to implement the copying using a long-tap gesture, like how the SMS app handles it. This was just about working, but it doesn't allow for arbitrary selection of text, the whole text is copied, or none is copied at all... Pretty black and white.
Solution 3: UITextView
My third attempt was to add a UITextView as a subview of the table cell.
The only thing that this doesn't solve is the fact that detected URLs cannot be handled by me. The text view uses UIApplication's openURL: method which quits my app and launched Safari.
Also, as the table view can get quite large, the number of UITextViews added as subviews cause a noticeable performance drag on scrolling throughout the table, especially on iPhone 3G era devices (because of the creation, layout, compositing whenever a cell is scrolled on screen, etc).
So my question to all you knowledgeable folk out there is: What can I do?
Would a UIWebView be the best option? Aside from a performance drag, I think a webview would solve all the above issues, and if I remember correctly, back in the 2.0 days, the Apple documentation actually recommended web views where text formatting / hyperlinks were required.
Can anyone think of a way to achieve this without a performance drag?
Many thanks in advance to everyone who can help.
As soon as I hit the submit button, a new idea hit me.
I was so preoccupied with having URLs inline with text and interactive that I didn't consider that maybe it's not the best solution.
I'm certain that to achieve that kind of behaviour, a UIWebView is the best choice, regardless of the performance issues.
However, maybe a better user experience / interaction is to not highlight the URLs inline, but to gather them into an array behind the scenes, and present a disclosure button as the cell's accessory view?
Then for selection and copying text, I could just use the UITextView with data detectors turned off and not worry about the links being sent off to safari and closing my app.
When the disclosure button is tapped, the user could be whisked off to the URL found in the text, or if more than one URL is found, present the user with a picker view to choose which to go to.
Any thoughts/criticisms of this idea are welcome.
You can prevent a textfield from being edited by overriding the UITextField Delegate methods such that they do not apply any edits. That leaves the field selectable and copyable but prevents alteration.
A better question to ask is: do you actually have to display the actual URL itself? Can you get away with just a page/location name, just the server.host.domain prefix or some other condensed representation of the url? I don't think anyone whats to try to read a long url on a mobile's restricted screen.
If you do need to display the entire url then I think that a detail view is the way to go.
What I am trying to do is create tooltip functionality so that certain words in my instructional app can be tapped and the definition pops up. For the popup part I plan on using code from “AFInformationView” which provides bubbles on the iPhone.
The part I'm struggling with is how to associate A particular word's location with the bubble. Currently I have the text on a UILabel that is on a custom UITableCell. Since I calculate the row height on the fly with:
[textToUse sizeWithFont:[UIFont systemFontOfSize:FONT_SIZE] constrainedToSize:CGSizeMake(stop-start, 500)];
I'm not sure what the coordinates for a specific word will be. I was thinking that if I created a custom DataDetectorType that could be the fix.
If anyone knows how to do this or has any other ideas I would be happy to hear them.
Thanks,
Andrew
I didn't create a custom UIDataDetectorTypes but Craig Hockenberry did something like it with his TwitterrificTouch.
He uses regular expressions to detect links and other things. I provide it with my keywords and then they become tappable. He places buttons on top of the matching text from the underlying labels. You can google a lot of posts that talk about "putting transparent buttons on top" of various things but Craig's code is the only example/working code I could find.
Here is the link:
http://furbo.org/2008/10/07/fancy-uilabels/
I don't think this is possible. The (few) Data Detector types that the iPhone currently supports are hard-coded with a integer type id. There does not seem to be a mechanism to extends that list of types.
File a feature request in their bug tracker. I will do the same.
AFAIK, you can't create custom data detectors.
The best approach for this sort of thing seems to be using UIWebViews. At least that's what I did. However, you shouldn't use a UIWebView inside a UITableViewCell. In fact, no subview of a UITableViewCell should respond to user input. So I think the best approach would be to display a UIWebView when the cell is tapped.
UIWebViews could be a possible approach but on scrolling you should consider that the whole text should be parsed to detect the words.You could use HTMl tags to make them blue and provide the links.But how could i then assign a custom behavior then opening in safari?
If you want custom data detector you could write an extractor method to primarly patch the links with help of NSregularExpression. For example
NSString regex = #"(http|https|fb)://((\w)|([0-9]*)|([-|_]))+(\.|/)"; to patch alll the links including Facebook URLs inside text like fb://friends.
Then you could use NSattributedString yo mark the links with different colors etc.
ThreeTwenty has a great library called TTTAttributedLabel where you could assign links to certain parts of a text. I also scrolls quite fast if you use it in tableviews
https://github.com/mattt/TTTAttributedLabel
We are trying to write a training manual application for the iPhone. On the top half of the screen is a diagram of a car engine, on the bottom half is some text. At the user repeatedly hits a "next" button, we highlight different parts of the engine, and in concert we highlight different parts of the descriptive text below.
We basically want "living text" in the text half, with the illustration following along on top to where the reader is in the text. What we'd like from the text is 1. user can scroll it using their thumb so possibly a UIScrollView 2. the software can explicitly drive a scroll to any part of the text (when they hit the "next" button). 3. the words in the text are interspersed with hotlinks e.g. "this is the camshaft... this is the piston..." and the user should be able to click on any of the keywords like camshaft, piston, and have the diagram highlight that. (The problem is not highlighting the diagram, its capturing the click). The text would have 300~400 buttons/links/keywords and about 600 words of text.
Since this is fairly similar to using a web browser, we tried using Apple's version of webkit using a UIWebView and handleOpenURL to register a service back to the app itself. But Webkit for internal links a popup comes up asking permission to access that link. Every single the user wants to go to a link (in our case just an internal event that we'd intercept so that we can highlight e.g. the camshaft). Tried to intercept the event from the HTML view, but that didn't work.
It seems like the best we can do is to abandon scrolling text, and make the text part more like flash cards or a power point presentation, breaking the text into custom UIViewCells with buttons inside a UIScrollView. However, this would impose an annoying constraint on the author that they would have to write everything to fit in the UIViewCells, sort of chunky.
Any ideas would be appreciated.
This is definitely something you can use a UIWebView for. Don't use handleOpenURL, rather, set your viewController as the webview's delegate, and override -webView:shouldStartLoadWithRequest:navigationType:. When this gets called, check the request, and pull out your link data from there.
It would probably be easier to implement that completely in JavaScript in the document you load in a UIWebView. You would have to use JavaScript (i.e. [UIWebView stringbyevaluatingjavascriptfromstring:]) anyway to achieve things like scrolling to a certain position.
Does anyone have any examples or resources where i might find information on scrolling text which is too long to display in a button control? I'm thinking something along these lines.
Display as much text will fit within the current rect with a '...' at the end to signify overflow.
Pause for say 1 second then slowly scroll the text to the right edge displaying the right part of the string.
Display as much text will fit within the current rect with a '...' at the beginning to signify overflow.
Start the whole thing over in reverse.
Is there an easy way to do this using the "core" or built in "animation" frameworks on a certain mobile device?
[edit]
Iwanted to add some more details as i think people are more focused on wether or not what i'm trying to accomplish is appropriate. The button is for the answers on a trivia game. It does not perform any speciffic UI function but is for displaying the answer. Apple themselves is doing this in their iQuiz trivia game on the iPod Nano and i think its a pretty elegant solution to answers that are longer than the width of my button.
In case its the '...' that is the difficult part of this. Lets say i removed this requirement. Could i have the label for the button be full sized but clipped to the client rect of the button and use some animation methods to scroll it within the clipping rect? This would give me almost the same effect minus the ellipses.
Here's an idea: instead of ellipses (...), use a gradient on each side, so the extra text fades away into the background color. Then you could do this with three CALayers: one for the text and two for fade effect.
The fade masks would just be rectangles with a gradient that goes from transparent to the background color. They should be positioned above the text layer. The text would be drawn on the text layer, and then you just animate it sliding back and forth in the manner you describe. You can create a CGPath object describing the path and add it to a CAKeyframeAnimation object which you add to the text layer.
As for whether you think this is "easy" depends on how well you know Core Animation, but I think once you learn the API you'll find this isn't too bad and would be worth the trouble.
Without wishing to be obtuse, maybe you should rethink your problem. A button should have a clear and predictable function. It's not a place to store and display text. Perhaps you could have a description show on screen with a nice standard button below?
Update with source code example:
Here is some ready to use source code example (actually a full zipped Xcode project with image and nib files and some source code), not for the iPhone, not using Core Animation, just using a couple of simple NSImages and a NSImageView. It is just a cheap hack, it does not implement the full functionality you requested (sorry, but I don't feel like writing your source code for you :-P), horrible code layout (hey, I just hacked this together within a couple of minutes, so you can't expect any better ;-)) and it's just a demonstration how this can be done. It can be done with Core Animation, too, but this approach is simpler. Composing the button animation into a NSImageView is not as nice as subclassing a NSView and directly paint to its context, but it's much simpler (I just wanted to hack together the simplest solution possible). It will also not scroll back once it scrolled all the way to the right. Therefor you just need another method to scroll back and start another NSTimer that fires 2 seconds after you drew the dots to the left.
Just open the project in Xcode and hit run, that's all there is to do. Then have a look at the source code. It's really not that complicated (however, you may have to reformat it first, the layout sucks).
Update because of comment to my answer:
If you don't use Apple UI elements at all, I fail to see the problem. In that case your button is not even a button, it's just a clickable View (NSView if you use Cocoa). You can just sub-class NSView as MyAnswerView and overwrite the paint method to paint into the view whatever you wish. Multiline text, scrolling text, 3D text animated, it's completely up to your imagination.
Here's an example, showing how someone subclassed NSView to create a complete custom control that does not exist by default. The control looks like this:
See the funny thing in the upper left corner? That is a control. Here's how it works:
I hate to say that, as it is no answer to your question, but "Don't do that!". Apple has guidelines how to implement a user interface. While you are free to ignore them, Apple users are used to have UIs following these guidelines and not following them will create applications that Apple users find ugly and little appealing.
Here are Apple's Human Interface Guidelines
Let me quote from there
Push Button Contents and Labeling
A push button always contains text, it
does not contain an image. If you need
to display an icon or other image on a
button, use instead a bevel button,
described in “Bevel Buttons.”
The label on a push button should be a
verb or verb phrase that describes the
action it performs—Save, Close, Print,
Delete, Change Password, and so on. If
a push button acts on a single
setting, label the button as
specifically as possible; “Choose
Picture…,” for example, is more
helpful than “Choose…” Because buttons
initiate an immediate action, it
shouldn’t be necessary to use “now”
(Scan Now, for example) in the label.
Push button labels should have
title-style capitalization, as
described in “Capitalization of
Interface Element Labels and Text.” If
the push button immediately opens
another window, dialog, or application
to perform its action, you can use an
ellipsis in the label. For example,
Mail preferences displays a push
button that includes an ellipsis
because it opens .Mac system
preferences, as shown in Figure 15-8.
Buttons should contain a single verb or a verb phrase, not answers to trivia game! If you have between 2 and 5 answers, you should use Radio Buttons to have the user select the answer and an OK button to have the user accept the answer. For more than 5 answers, you should consider a Pop-up Selector instead according to guidelines, though I guess that would be rather ugly in this case.
You could consider using a table with just one column, one row per answer and each cell being multiline if the answer is very long and needs to break. So the user selects a table row by clicking on it, which highlights the table cell and then clicks on an OK button to finish. Alternatively, you can directly continue, as soon as the user selects any table cell (but that way you take the user any chance to correct an accidental click). On the other hand, tables with multiline cells are rather rare on MacOS X. The iPhone uses some, but usually with very little text (at most two lines).
Pretty sure you can't do that using the standard API, certainly not with UILineBreakMode. In addition, the style guide says that an ellipsis indicates that the button when pressed will ask you for more information -for example Open File... will ask for the name of a file. Your proposed use of ellipsis violates this guideline.
You'd need some custom logic to implement the behaviour you describe, but I don't think it's the way to go anyway.
This is not a very good UI practice, but if you still want to do it, your best bet is to do so via a clickable div styled to look like a button.
Set the width of the div to an explicit value, and its overflow to hidden, then use a script executing on an interval to adjust the scrollLeft property of this div.