I am sorry if I am going off topic, this is not a question about code, but I am having troubles with constraints
In my app I use a UIImageView as background, I set the constraint for the image to fit the screen and it works
But after that i have a lot of labels and buttons,and if i add even one constraint to one of these elements,it disappears or goes out of the UIImage
I want to set the UIImageView as background,so all the other elements can be placed on the image using constraints ,how do i do it?
To simplify the process can i group all of my interface elements in some views and then apply the constraints to the view?
I need a good explanation and/or tutorial about this elements, at the moment my interface on iPhone 4 fits ok until the iAd shows up, and on the other iPhones there is a lot of empty space
take a look at this tutorial. Hopefully, it will works.
http://www.raywenderlich.com/83276/beginning-adaptive-layout-tutorial
Try this: with one of you elements, cmd+click (or right-click) on it and drag upward until the background UIImage is highlighted. Release and select 'left'. This sets a pinning constraint to the left side of the background image.
Then cmd+click and drag to the side, and select 'top'. This should pin your element to an intelligible spot; it may still need some sizing help, but at least you will be able to guess where it will show up.
Related
I'm having some issues with the constraints in my app. Here is how it looks on the iPhone 4 (that's how i want it to look, and how i usually setup my interface, is this the proper approach or not?)
Now, when i switch to the iPhone 5 screen it looks like this
and as you can see, the blue dots (which is UIButtons) are not placed where i want them to be. I made my constraints rely solely on the right side of the view (since that is the one re-sizing, i found that in order for you'r views to align themselves accordingly, it doesn't help to align them to the left side). I don't really know how to fix this. I am finding this new iPhone screen to be a real pain in the arse. Any good advice on how to work with this new screen without a lot of headache would be appreciated :)
Thanks on advance
It looks to me like the are still the same distance from the right side of your view, as you said you set them to be, while the background has stretched to fit the new size. I suspect it's actually the background that isn't doing what you want it to do (keep the same aspect ratio and show more stuff on the left), or try keeping the buttons relating to left and right to stay aligned with the stretched background image.
I'm trying to build a custom, reusable UIScrollView that can be added to multiple views. The scroll view is going to be a weight picker. For the life of me, I can't find a decent example for how to implement this neatly or cleanly.
I would love for someone to point me to an existing library or tutorial that shows me how to do this. I've hacked apart a few examples, but so far, nothing is very good or reusable. Please help!!
For what it's worth, I have an image that individual ticks for the weight. So I can select to the tenth of the number (e.g. 160.4). The image has the first tick bold and larger than the remaining 9. I'd like to have the weight/number centered over the large tick. I'll update the points to my label/datasource after scrolling stops.
UPDATE
I need to make this. I have the custom font, background, and ticker image.
I would not do this through an UIScrollView. I think it would be more complex and you would certainly end up having issues when trying to add you custom picker into another scroll view.
What I would do is:
building the picker view by means of a series of CALayers, each one representing a "building block" of your picker view; see attached image:
each building block would represent a specific value by mixing a UILabel (the text) and an image;
use a pan gesture recognizer, or alternatively define touchesBegin/Moved/Ended method to deal with panning;
when a pan is done, you displace the view content to the left or right according to the panning;
when panning, you also add new building blocks to the left or right end of the picker to account for empty areas that would be revealed by the displacement done at point 4.
I think that having a look at another kind of custom control source code would be of great help to you. You would not possibly find your custom picker already implemented, but could get some guidance. Have a look then at cocoa controls.
Hope this helps.
If I were going to implement this, I would create a really wide image that had every weight on it I'd ever need - I would probably create this in code when the app started up. This image is then used as the contentView of your picker. You get all the scrolling features "for free", and you could even update the values shown in the other parts of the view during scrolling (or dragging.
The scrollView is just the area with the tick marks and weight numbers, and resides in a subview above the background, but below the centered vertical line that shows the actual weight.
EDIT: on second thought, forget the image. If you have the code to draw the image, you can do the drawing in a custom UIView. So you get the draw rect, you know the contentOffset, so you can draw just what you need.
My app is behaving sluggishly. If i pop up a UIActionSheet, for example, instead of rolling in smoothly, it stutters in over about 5 frames. I know ideally you should have as little amount of views on screen as possible, but that's what I've got anyway.
Any suggestions for speeding it up?
EDIT:
On my view i have:
Custom navigation bar in place of the regular one. It's a UIImageView, using an image file. It has a quartzcore shadow. It contains 3 buttons. 2 of these buttons have 2 UIImages each, for normal and highlighted, generated from code when the view is shown. The other button uses an image file for normal and for highlighted.
An image file for a background lies under that. On top of the background is a UITableView. By default, it doesn't have any cells (the user adds them). We'll ignore the cell, since it's slugging regardless of their being there or not.
The header of the tableview contains some labels, and an editable uitextview. The size of the header changes as more lines are added to the textview. It also has a background image, which is transparent to allow you to see the view's background image behind it. It's loaded from a file, and a texture image on top of that is also loaded from a file.
The footer is simply a background image loaded from a file with the same texture on top.
Andrew, I'm afraid you haven't been quite specific enough to isolate the exact problem. However there are a couple of things I have picked out. Firstly, check your table view is set to be opaque. Also try to design your app so your table cells can be opaque. I'm assuming your design will allow this. You need to really know how to optimise view rendering performance if you want your table and it's cells to appear translucent over other content and it may be you would need to develop your own custom specialised alternative to UITableView if that is something you really need to know (can be done but quite advanced stuff).
Also you mention using Quartz shadow. You should be able to use UIKit for drawing shadows around images, unless you have some specialist requirement. Are you sure you need to use Quartz for what you want to do? Apologies if you already know this, but if you are fairly new to iOS development and have been looking up how to do shadows, you may have found the Quartz API's for doing that and assumed that is the solution, when (depending on what you need) you will probably be better off staying with UIKit. As a general rule of thumb, only use Quartz if you are sure you can't do what you want to do with just the UIKit API's.
Another thing to check. If you are using Quartz, then you are probably getting getting the graphics context for the UIImage view and drawing on the views context in drawRect: depending on how your view hierarchy is configured, and if you have your navigation bar view set to be transparent over the top of the UITableView, then your custom drawRect implementation may be getting called unnecessarily with every animation frame and this would be a big drain on performance.
Given the level of information you have given I'm having to guess a bit and can't give a precise answer. However for a definitive understanding of how to optimise UIView performance I recommend checking out this video (though you will need an Apple Developer account to be able to access it):
https://developer.apple.com/videos/wwdc/2011/
Session 121 – Understanding UIKit Rendering
Hope this helps. Paul.
What I'm trying to do:
The bottom (and top) cells of a "grouped style" UITableView have rounded corners - as is the default in many Apple iOS and non Apple apps. Sometimes cells are inserted via an animation, i.e:
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationTop];
Now this works fine. Except: When a cell is inserted below the bottom cell, or above the top cell (for a grouped style table) - there seems to be no smooth animation.
The Problem:
What I mean is that the corners of the top/bottom cells need to animate from rounded to unrounded (as they are no longer top/bottom) - and this happens in a very jerky and unlike Apple fashion.
Does Apple ever do this in an App - if so, how do they do this smoothly? Otherwise, how could this be done right?
NB - I know this is a pretty minor detail, but I'm a bit of a perfectionist...!
Take a look at the Weather App that comes with iOS, in the flip side view where you configure your cities you will see a table that accommodates these animations. As Mark Adams points out, in iOS5 there is an enum for the OS to auto-detect which animation should be used. If you want to target pre-iOS5 then on your delegate method that commits deletion you should determine what cell is being deleted based on its row position, if its 0 you would use UITableViewRowAnimationBottom if it is the the last row you would use UITableViewRowAnimationTop and if it is somewhere in the middle you would likely use UITableViewRowAnimationTop so that the group shifts upward with the animation, you might want to play around with this though.
Sorry I don't have time to write actual code out and test it, but maybe I can give you a lead. You're basically asking to set the corner radius on only two corners of a cell, then fluidly animate them to sharp corners as they move toward the center of the table.
One way to do that might be to define your custom UITableViewCell with a CAShapeLayer as the background. CAShapeLayer is drawn from Quartz paths: see http://developer.apple.com/library/IOS/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_paths/dq_paths.html#//apple_ref/doc/uid/TP30001066-CH211 . CAShapeLayer's path is animatable, but not with implicit animation. You'll need to use CAPropertyAnimation or perform your own interpolation. In my experience, for example in http://itunes.apple.com/us/app/blaster-through-asteroid-field/id414827482?mt=8 , doing your own interpolation is faster and more reliable (but other than the interpolation and collision detection everything most of the game relies on quartzcore, so I don't think you'll have a performance issue).
SUMMARY: Custom cell has CAShapeLayer backing. CAShapeLayer has path with 2 rounded corners. You animate the path property as the position of cell moves toward a certain point on screen. Done, smoothly animated rounded-to-square corners. Let me know if you try it out :-)
Other references:
http://developer.apple.com/library/IOS/#documentation/GraphicsImaging/Reference/CAShapeLayer_class/Reference/Reference.html#//apple_ref/doc/uid/TP40008314
http://developer.apple.com/library/IOS/#documentation/GraphicsImaging/Reference/CGPath/Reference/reference.html
As there's no real (code complete) answer currently, here's a list of the best workarounds.
Change your interface so that this jerky animation never happens.
This might mean using a plain style tableView as opposed to grouped
style, or using the alternate style seen in the Weather app (see
Chris Wagner's answer. Thanks Chris!). It might even mean using a
completely different interface that doesn't incorporate this
animation - this was the solution I went for, I managed to work out
a UX alteration that is possibly even better than the original.
Deal with it. Apple seem to, in some of the less used parts of
the OS or their apps.
File a bug report on bugreport.apple.com. It would be nice if Apple
fixed this... I know it's a pretty minor detail, but that's why I
like Apple products - cos they get the little details right!
Create a custom UITableViewCell subclass. I've thought a bit about
this, and while it's a bit of a programming challenge, I think it's
doable. Here's how: EDIT: See Rab's answer for some more detail. Still haven't coded it out yet but may give it a go when I get some time.
The custom cell has a property that defines whether the cell is a top, middle, or bottom cell. This can be set by a UITableViewController (or subclass etc).
The backgroundView property of the custom cells can be custom drawn using quartz for the rounded corners etc.
Whenever the property that defines the position of the cell is altered, the change to backgroundView can be animated. The hard part
here is animating the curve of the corners... is this doable? Apple
seems to do it in the corners of notification center, when it is
pulled down and pushed up - so seems like it is possible.
If someone seriously want to do this, and put the code on gitHub... you would be awesome! And you would have bettered
Apple's UI ;)
Have you tried to insert two rows at a time? The one on the top with zero height, and the next with rounded corners (you can use quartz core for that)
If you check the Tags section of the 'Send to Youtube' part of the Photos app, you'll see apples animations are just as 'jerky' as the rest of ours. (obviously you need a video to upload to youtube)
I'll assume thats what you were thinking of...
I am brand new to iPhone app development. I am trying to create an image reader using UIScrollView. I need to focus a portion of an image and hide the rest. Till now I am only able to focus required part of an image but have no clue how to hide the rest. I had a suggestion that, I need to add four views at top, bottom, left and right. I need to hide those as per requirement. But, I was able to go no where with the suggestion. Can you please tell me how can I implement the functionality?
I don't understand what you really want to do. But if you think putting for views above I might suggest you use mask image for the same. Use alpha component.
Atlast I was successful in hiding part of an image. I used four views with background color and resized them according to the portion I need to display.