I see other properties of an object (subview array, gesture recognizers, tag, etc.) in the debug area when I add a breakpoint, but can't find the "frame". New to using breakpoints and debug features, can't figure this out. Just want to be able to examine the frame of a UIView at a breakpoint. Thanks.
The debugger's variables pane doesn't show everything, unfortunately. The easiest way to print out the frame is to NSLog the view itself. UIView's description method prints the frame values as part of the NSLog message.
If you don't want to put an NSLog in, when you hit the breakpoint you can also do po nameOfView in the gdb console. That's the same as NSLogging it or calling -description.
Related
Was hoping someone could help with this please? I've scanned through the forum and apple docs and can't find anything that matches my problem exactly.
I'm trying to animate a custom 'Composite' UIView derived class (with overidden drawRect) by changing a custom colour property (not one of the standard view properties like centre, alpha, backgroundColour etc), calling setNeedsDisplay and redrawing the view using drawRect over X seconds duration to produce a slow colour change from say, red to blue.
At the moment, all Composite::drawRect does internally is clear the context (the view has a default background colour set to clear) and fill the view using the colour provided. This works fine the first time it's called - the view appears on screen in the correct red colour.
My problem is that when I try to animate the view by updating the colour property, even though drawRect is being called everytime I call setNeedsDisplay and the colour being fed into the view instance is correct the view doesn't update on screen until I stop calling setNeedsDisplay (or rather, stop updating the custom view colour property). It's like every call to setNeedsDisplay pushes the view to the back of a list so it doesn't get updated on screen until it stops getting called (even though drawRect is being called).
For example - trying to change the colour from red to blue over 10 seconds, the view stays red for 10 seconds, then turns to blue in a single frame at the end of the property changing (and presumably when I stop calling setNeedsDisplay) rather than a slow fade between the two over the time duration.
Any ideas what's going on? I'm guessing I need to animate this using apple's own animation property stuff but I'd really prefer not to - I'm trying to make this cross platform if possible and I don't see why my own method shouldn't work.
The basics:
In case it matters, my composite view instance is a subview of an UIImageView. (I know imageview drawRect doesn't get called but I can't imagine this is a problem for it's subviews - after all, my Composite::drawRect is definitely being called).
I'm setting the right colour on my view instance - I've debug printed this to be sure - so the colour provided to the view goes from red to blue over however many seconds / frames.
I'm setting setNeedsDispay and drawRect is being called every time - again, debug printing confirms this.
This is happening over multiple frames and the app goes through the drawing update at the end of every frame - I.e I'm not blocking the render thread or anything - the app runs fine, it just doesn't update the view on screen even though its drawRect is being called, until I stop manipulating the property. Someone mentioned a similar problem where they were blocking the render thread in a single frame but I'm definitely not doing anything like that.
I've tried messing around with the following but they all produced the same results (i.e. view changed from red to blue in a single frame rather than a slow change over).
Updating the colour every frame but only calling setNeedsDisplay on my view every Xth frame (5, 10, 20, 30 etc)
Updating the colour every frame but not calling setNeedsDisplay unless the corresponding drawRect call from the last setNeedsDisplay has happened (i.e. set a flag to false in SetColour func, set same flag to true in drawRect, test against it when decided to call setNeedsDisplay) - same results.
setting the view bounds with ContentMode set to redraw to force an update - same results
tried calling setNeedsDisplay on the parent image view too - no change.
I'm guessing that this just isn't possible - can anyone explain why its not updating the v view onscreen even though drawRect is being called? Any ideas how I should do this? I don't think I would be able to do what I want to do if I tried animated one of the default view properties using apple's internal animation system but if I've got to use that....
Thanks!
:-)
Forgive me if this is a duplicate. I thought for sure this would be an obvious question.
I have a container in a storyboard, which is of class ModelViewController (the whole view controller). From ModelViewController I need to get the width and height of the container. I am currently trying:
self.view.bounds.size
Which yields 0.563380 and 0.000000. I also tried
self.view.frame.size
Which yields the dimensions of the entire screen. What am I missing here?
From this post
View frames are not actually useable in viewDidLoad; you should move all of your geometry-manipulating code into viewWillAppear. The system will clobber any changes you set in viewDidLoad between there and when it's about tom come on screen.
And the comment
Actually, you should move geometry changes to -viewDidAppear pre-iOS 5 and to -viewWillLayoutSubviews for iOS 5+. -viewWillAppear: may not actually have the correct bounds/orientation if the view is being animated.
I found the solution. The correct dimensions are indeed given when called from viewWillLayoutSubviews. I was calling from viewDidLoad giving incorrect results.
I have a UITextField with custom keyboard, basically like a calculator. I would like my keyboard show up by default, so i used [self.topInputTextField becomeFirstResponder]; in viewDidLoad, I think that's very common usage. However, it causes some very weird actions on my textfield.
When i set my textfield as the first responder in viewDidLoad, and every time after i done editing, the text will jump, and when i click another text field and and click the first text field again, the texts in the first text field sometimes shift down and disappear, but sometimes not. I feel it's very hard to describe, so i recorded a GIF image for it.
And the reason, that I am sure [self.topInputTextField becomeFirstResponder]; causing the issue, is when i comment that line of code out, everything back to normal. here is the GIF after i comment out that line:
that's vert strange to me, between 2 GIF file, the only change i did is comment out that line of code. I couldn't find any solution on SE. Any idea would be very appreciated.
Edit:
One more thing is I tried to change font, and font sizes, they all have similar strange behaviors.
*Edit 2:**
here is how i set up my textfield,i didn't do anything fancy
Try calling the keyboard in viewDidAppear, this method gets called after viewDidLoad. I assume it's because you should only call the keyboard on a loaded view that has appeared to the user, so if you call it before the view actually appears it will cause unexpected behaviour.
viewDidLoad is too early for calling this, the UI hasn't worked out which size your screen is, or even which orientation your device is in. It isn't yet a UI really... Try it in willAppearAnimated: ..
While using cgdb, how does one scroll through the output visible in the gdb window?
PgUp and PgDn should scroll the gdb window. If they don't, check your TERM environment variable and make sure it's set correctly.
hi i am observing something weird in iOS custom views, where i have a button in side a custom view, i am looking for documentation or your answer to explain why i have this observation
i have a custom view (subclass of UIView), it contains a simple button, i bind the button touch event via addTarget:Action with UITouchUpInside, i just bind it selector to a simple method that NSLog a message
if you display the custom view and hits the button, you can see the message in the console, everything works as expected.
However, if you add a UIGestureReognizer to the custom view, and run it, when you click the button, it no longer prints the message, WHY???
i did more in depth investigation, and by looking at the hittest method IN THE CUSTOM VIEW (the view contains the button) (i override it, but i didn't do anything, i just call super again), the hittest is returning the correct view, i.e. when i click on the button, hittest method of the custom view is returning UIButton
i do not understand the event chain here, can someone pointing the documentation that explains this?
it seems to me when you add the regonizer to the container view of the button, for some reason, the button DOES NOT KNOW how to handle the event, so it asks its superview (custom view in thsi case) to handle it, but why?? i already bind the event handeler to the button via UITouchUPInside
please please help i want to understand this
Set your recognizer's cancelsTouchesInView property to NO.