I have a UITextView that I'm trying to keep hidden from the user, except I'm using it's autocorrect interface so I can't just put it's hidden property to true.
Currently I am putting the contentOffset such that it hides the first line of text, however this does not consistently work. Sometimes it does, other times the scroll view re scrolls to where the text is partially visible. It seems arbitrary which it does, as without changing a line of code, the behavior will switch by itself after I rebuild...
I have tried turning off scrolling for the UITextView, as well as overriding the UITextView's drawRect function to not do anything, as well as changing the TextColor of the UITextView to clear color. It seems that you cannot change the alpha values of text colors so that did not work.
Any other ideas on how to achieve this?
Thanks in advance.
Perhaps the UIScrollView is trying to be smart about where it is automatically scrolled to, even though you have disabled user scrolling?
You could try manipulating the contentOffset, and see if controlling that value stops the unwanted scrolling.
Another idea to help debug any unwanted scrolling activity is to add debug NSLog statements into a few of the key methods of UIScrollViewDelegate, such as scrollViewDidScroll: or scrollViewShouldScrollToTop:. If the contentOffset approach fails, this might help you understand what is going wrong, and possibly prevent it at the delegate level.
By the way, it sounds like what you're doing in general is kind of hacky. You might end up with more to-the-point answers (and cleaner code) by just asking about your true goal - maybe having your own version of spell checking?
Related
I have a custom subclass of UIButton that I want to re-use in multiple projects, some of which use interface builder and storyboards, and some of which may not. It involves setting the button's frame in several places.
If I add
self.translatesAutoresizingMaskIntoConstraints = YES;
in the initialization, everything looks and works right, however, I get:
Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
Will attempt to recover by breaking constraint…etc
logged to the console. However, if I set
self.translatesAutoresizingMaskIntoConstraints = NO;
none of the button sizing works and the button is completely broken.
Is there a way I can suppress the error since it seems to degrade to the right thing or can I somehow manually remove the offending constraint?
I've tried dumping the constrains after the button is initialized, however, it does not seem to contain the constraint AutoLayout ends up breaking.
Edited: Below are links to a sample project and then my button code. It works great when auto layout is turned off in the storyboard, however, when auto layout is turned on, the buttons seem to position at the origin (seems to be because when initWithCoder is called, the buttons don't have superviews or any position information).
http://www.kudit.com/dump/KFB.zip
http://www.kudit.com/dump/KuditConfirmButton.zip
Your guess is correct, in that when the buttons are initialized from the storyboard (using initWithCoder:) the frame is zero - this is expected for views using autolayout - frames don't get assigned until later on.
I have your sample project mostly working under autolayout by creating a boolean ivar called hasSetup, which get set to YES inside the setup method. The setup method doesn't run if the frame is zero. I also call it again from layoutSubviews. This gets around the not-working-when-using-autolayout in storyboard problem.
The various layers still aren't the correct size though. You may want to look into resizing them from layoutSubviews.
You also can't use setFrame under autolayout - you need to make sure any constraints on your view (like the sizing constraints from the storyboard) are adjusted instead. It's going to get quite messy dealing with both possibilities.
They look really good though - hope to see them on GitHub when you've sorted these problems.
I'm using a UIScrollView to display a custom UIView. When the user drags a finger across the UIScrollView, there is a noticeable delay before the display begins updating. If the user keeps touching the screen, the UIScrollView becomes very responsive after a short time. Subsequent attempts to scroll result in the same initial delay, followed by high responsiveness. This delay seriously affects the usability of the view and I would like to get rid of it.
In a test project I have written to try to get to the bottom of this issue, I have only been able to partially replicate the behaviour. The first time that the user scrolls is exactly the same - however any subsequent attempts to scroll are responsive straight away.
I have tried both setting delaysContentTouches = NO and subclassing UIScrollView so that touchesShouldBegin returns NO as suggested in multiple places online, but neither has worked.
I'm using MonoTouch on iOS 4.3, but Objective-C answers are fine. I would post code to help illustrate the issue, but since I have been unable to narrow down the problem this would be well over 1000 lines. Hopefully this is enough info to get a solution.
Does anyone know what might be causing this delay, and how I can get rid of it?
Some general suggestions for improving scrolling performance.
Have your scrolling views rasterize offscreen:
myView.layer.shouldRasterize = YES;
Set that property for each sub-view on the scrollview - do not set it for the children of those sub-views or you just eat up memory that way.
If your scrolling views do not need compositing, make sure you turn that blending off:
myView.opaque = YES;
Test using the simulator by leveraging these two features that appear on the Debug menu of the iOS Simulator:
Color Off-screen Rendered
Color Blended Layers
If that doesn't address your problem, and you have implemented UIScrollViewDelegate, double-check to make sure you are not doing anything time consuming in those methods - for example, based on your description, you might be doing something in scrollViewDidScroll, scrollViewWillBeginDragging, or scrollViewWillBeginZooming and if you are, optimize that so it happens before scrolling even begins. Also, make sure you're not doing anything in touchesBegan.
I suspect what is happening is there is some kind of interaction enabled in the content of your scroll view.
The system does not know if the initial touch down is going to be a tap on one of the subviews or a drag on the scroll view, therefore is causing a delay while it waits to see if you are going to lift your finger.
What are the subviews of the UIScroll view?
As an experiment set all the subviews of the UIScrollView to have userInteractionEnabled = NO, this will not be what you want, but its just a test. Is should scroll fine after this, otherwise I am wrong.
I've decided that I don't want to ever use UIPickerView again... it's completely inflexible in terms of functionality, design, and size (height). It also occasionally gets stuck between rows, and the delay that occurs between letting go of a wheel and when the delegate method is fired indicating that a new row has been selected (because of the "settling in" animation) has caused lots of problems in the context of the apps I've been working on.
That being said, the user-friendly aspects of UIPickerView are good, and I'd like to try to replicate it. I've tried to research different ways that this might be done, but without much success. Does anyone have any ideas as to what would be involved to make something similar from scratch?
I was trying to get a UITableView subclass to behave in such a way that whatever cell was currently in the middle of the table (it would change while dragging, etc.) would change its background colour to something different implying that it was "selected". As soon as the table was dragged such that the "selected" cell was no longer in the middle, the cell would go back to normal and the new middle cell would change colour. So this would be like UIPickerView in a sense that you don't have to tap on a cell; instead you just drag to have one selected by default.
I figured it should have been easy enough to intercept the "touchesMoved" method of UITableView and add some code that looped through all currently viewable cells in the table, checking to see if their frames overlapped the center point of the table, and changing their appearance accordingly (plus sending a notification to other classes as needed to indicate the "selection" change). Unfortunately, I can't get this to work, as the "touchesMoved" method doesn't get called when I drag the table. Am I missing something obvious?
Any ideas or suggestions would be very much appreciated at this point... I made an app that relied heavily on UIPickerView objects, and because of the problems I've run into with them, I'll have to abandon it unless I can figure out a way to make this work.
Thanks very much,
Chris
Remember that a UITableView is a subclass of a UIScrollView, and the UITableViewDelegate gets all the UIScrollViewDelegate method calls too. scrollViewDidScroll: sounds like it would easily fit the bill for knowing when the table view was scrolled.
As for finding which row is in the middle of the view, just use indexPathForRowAtPoint:.
I'd like to create a UITextView that you can tap anywhere within it and start typing at that location. The default behavior of the control is that typing starts where the last character ended. So, if I had a UITextView with no text in it and tap in the middle of the control, I'd like typing to start there--not in the upper left.
What is the best way to implement this behavior? I've considered making the default text value of the view to be 3000 space characters or something similar, but this seems like not an elegant solution. Suggestions?
I suggest deriving from UITextView to create a custom view that handles taps. You'll want to override the following methods, probably:
touchesBegan:withEvent
touchesMoved:withEvent
touchesEnded:withEvent
touchesCancelled:withEvent
Make sure the userInteractionEnabled property has a default value of YES. Override hitTest:withEvent and pointInside:withEvent to figure out where in your view the user tapped.
Be sure and read the Responding to Events section in the View Programming Guide for iOS, and also see the Event Handling Guide for iOS for more details.
Anyway, once you figure out where the user touched, you can modify the text or reposition the karat as appropriate.
I'm building an iPhone application and like most I am trying to implement a UIScrollView with a UIPageControl, however I am coming across a very quirky behavior, which I assume may be a bug. Hopefully one of you has seen this before because it is driving me nuts.
Basically, the page control works fine, everything is hooked up and works normally on all accounts EXCEPT, with certain placements of the UIPageControl within the UIView, the UIPageControl will cease to render.
I'll just take screenshots of the XIB window to help illustrate... here's a placement that works perfectly fine:
http://www.jasconi.us/prob1.png
The UIPageControl is placed physically above the UIScrollView. Works great, everything is visible and working.
The next two DO NOT work:
http://www.jasconi.us/prob2.png
http://www.jasconi.us/prob3.png
The first one is simply placed below the scroll view. Doesn't render at all.
The second one is placed above the scroll view without technically being inside of it. Also doesn't render.
What the hell is up with this? I've tried using
[[self view] bringSubviewToFront:pageControl];
...to no avail.
Any ideas?
OK I found the answer to this, it's a little six degrees of Kevin Bacon.
This isn't actually a software bug, but a XIB quirk, for some reason the lower placement of the page control in combination with the default settings for autosize and anchor seem to jettison the control into outer space.
If you turn off all auto-scaling and auto-sizing and auto-anchoring and all that other crap, the controls appear exactly as you expected. The fact that it appears reliably when placed above the ScrollView is an oddity.
shrug.
Hope this helps future iPhone initiates.
Did you check to make sure that numberOfPages is not 0?
If you set a breakpoint can you see that pageControl is not nil?
I was still encountering this exact same problem, even after trying everyone's posted answers. My issue ended up being a little more "DOH":
I was using UIPageControl at the bottom of a modal FormSheet, however, I forgot to set the size of the view as Form Sheet in the xib. This caused my page control to be off the screen and never visible.
Moral: set view size (Full, Form, Page, etc) in your xib on the base view.
This will sound like a real no brainer, but I got caught out by it.
By default, UIPageControl expects to be on a dark background. IE: The dots are light gray, and white for the current page.
I used UIPageControl on it's own with no scrollview to change the time range of a graph I was rendering with drawRect:
Long story short, the graph background was white, so the page controller worked, I just couldn't see it. The solution was putting the graph itself in a subview, and making the parent that contained the page control have a dark background.