UIWebView performance compared to UIScrollView with many labels - performance

in an iOS app I have to display a list of text items that are stored as strings in an array. Since the lines of text would be formatted differently (size, color), I tried two different approaches:
create an UIWebView, make a htmlstring at runtime from the strings in the array and format it with a loaded css file
create an UIScrollView, and create an UILabel for every string AND add an UIImageView with an image of a dotted line after each label (which I do with css in the approach above)
I expected very poor performance from the second approach. BUT it seems the scrollview with the labels (ca. 100) an images scrolls smoother and is more responsive than the webview.
How could that be? I do nothing in the background, just display this view. Thanks a lot!

If I'm not mistaken it's because UIWebView doesn't pre-render anything.
Meaning - UIScrollView caches all your data for smooth transition while UIWebView renders it as it enter the view.

Related

NSImageView rending a blurry NSimage despite it being of the same size

I have an NSCollectionViewItem with an NSImageView (32x32) to which i supply a #1x image of the same size.
It looks perfect in the interface builder, but when the app is built, the resolution looks quite off. Is there any particular reason for this?
Just to add that the Image in the asset manager also has a #2x
EDIT: Still investigating this issue, but I have just noticed that If the collection view which contains the collection item, which contains the NSImageView is enclosed by a bordered NSSCrollView the images are perfect (.ie non blurry)
Turns out if you draw images in frames with either the x,y coords or the height and width having fractions you end up with blurry images. passing the drawingRect through NSIntegralRect fixes that.

Famo.us images carousel

How can I create simple image carousel. Let's say I have GridView with two rows and one column. I want to create image carousel in upper row. Can I do that with ScrollView. Any sugestions?
You have the right idea. You can use gridLayout just to keep your sizing in line, and using scrollView is perfectly fine.
I do not know exactly how you imagine such a carousel working, but one option to be aware of in scrollview is the 'paginated' option. This allows you to easily define target positions for scrollview to stop and snap to, similar to a scroll picker on native. Or if you want the sources definition..
* #param {Boolean} [paginated=false] A paginated scrollview will scroll through items discretely
* rather than continously.
The next thing you may want to think about is how a carousel goes round and round and never reaches an end like scrollview would. There is no option for this by default, but I found a way it can easily be done. It may be a bit trickier with smaller images, but here is an example I did for a infinite panorama.
Transforming Panoramas for Virtual Tours with famo.us, has it been done?
The trick was to use a second duplicate image trailing the scrollview and when scrollview was in the right position, we could jump it back to the beginning, with no visual evidence to the user.
Here is the live example..
http://higherorderhuman.com/examples/infinite.html
Hope this helps you get started!

How to resize between 3.5" and 4" screens (dynamic constraints in autolayout?)

I have one view filling the screen with a background image. Other views (text fields) are in exact positions (the background image includes the text field background images). When I change from 3.5" screen to 4", the text fields don't change in the same way that the background resizes. The bg image simply resizes to fill the screen, but the text fields jump out of alignment.
Is there a way to have two sets of constraints, one for each screen size? or is there a way to have views resize proportionally to another view?
EDIT:
Is there a way to have two sets of constraints, one for each screen
size?
Yes, by adding constraints programatically and checking [[UIScreen mainScreen] bounds] to get the screen size.
or is there a way to have views resize proportionally to another view?
Yes, you could set this up in interface builder. But it will be hard to manage, I would manage the constraints manually in code since you are using a custom background image the textviews need to position exactly
You're going to struggle to get these things to line up properly with the text view backgrounds being part of the background image.
You should amend your image assets and use the background property of UITextField to have an actual background image, and remove the boxes from your main background image. The icons could be separate images as well.
Failing that, it would make more sense to have the image stretch underneath the text boxes rather than on top.
Your layout is doing what it should do based on your description, but the image isn't stretching in the right way. In your screenshots, username is always the same distance from the top, and the others are the same distance from the bottom, but that isn't how image stretching works. I don't know how you've set it up but it would make sense to have a single image the size of the 4 inch screen, which has the bottom cut off for 3.5 inch devices, and constrain everything from the top.

cocoa mac osx grid display of images of different sizes

what i'm trying to do is displaying a set of images in a grid like fashion but with different sizes as for images in landscape or portrait position, this excludes using the NSCollectionView because the item prototype's size can only be set once...
i'd go and add subviews programmatically to a scrollView but this yet again when the window's size changes and the scrollView get a bigger width, there will be just blank spaces on the right side...
you can checkout the image below for a better understanding...
http://i.stack.imgur.com/NVJjP.png
thanks in advance you guys...
what i ended up doing was implementing a purely mathematic algorithm where i calculated the (x,y) position for every new added photo depending on the previously added photos and it did a pretty good job... the container holding the photos was embedded in a scrollView, needless to say that i had to calculate the height of this container as well.

How to determine size of page in uipageviewcontroller landscape?

I am working with the default UIPageViewController template from Apple. Basically just dabbling with it to learn how it works.
I would like to load a background image for the dataview controller and resize automatically it according to the orientation (rather than loading different images).
Is there any quick way I'm missing to determine the size of each page in landscape orientation? I don't mean
self.pageViewController.view.frame
which seems to give the size of the entire view including both pages, but rather the size of one of the two pages shown in landscape orientation. I've achieved more or less what I need with something like this
CGRectOffset(CGRectInset(self.pageViewController.view.bounds,125,0), -125, 0)];
but surely there must be some better way? This feels like an ugly hack.
Thanks in advance!
I havent worked with the split view UIPageViewController yet, but as I understand it, you'd pass in two views which would be rendered as the two pages. So why not let the page views determine the size of the graphic itself based on how the UIPageViewController has set it in the frame?

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