Cocoa touch dimming background darker - objective-c

Hey! I am making an app with a slider which slides out from the bottom and I would like to make other parts of the app a bit darker to show that the picker is the active component, like when alertbox comes, the background darkens. How do archieve this?

Overlay the elements you want to darken with a view that has a semi-transparent dark background (e.g. a black background with an alpha value of 0.5).

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How to fix White Screen after Splash Screen in React Native for iOS

For Android, I made the color of the white screen the same as the Splash Screen color. So how do I change the color of the white screen on iOS?
use react-native-bootsplash or implement splash screen by your own.
you can change the bg color of splash screen using xCode, find and select the .storyboard that is currently used in your project.
from the right side of your x code controls, you will see background prop, from there you can change it.

When screen orientation changes, I want only one element to rotate

I'm making an app with react native, expo, bottom-tab-bar navigation package, and expo-screen-orientation package.
The app is for reading some text that is inside some View elements in the middle of the screen, and is controlled with the bottom tab bar.
When I rotate the phone, and change the screen orientation (portrait-landscape), it kind of messes with the UI layout.
What I'd like to achieve, is to only have the View element that contains the readable text to rotate when the phone changes orientation, but the rest of the app (The bottom tab bar, background, buttons, etc.) to stay in the 'portrait' orientation.
What I've tried so far is this:
I've tried to lock the screen to portrait with
ScreenOrientation.lockAsync(ScreenOrientation.OrientationLock.PORTRAIT);
and then listening to orientation changes with eventListeners, Dimentions, useWindowDimentions, and expo-screen-orientation's ScreenOrientation.AddOrientationChangeListener(Listener),
and then maybe rotating the View element manually.
But if the screen is locked and not rotated, the change is not detected.
I've looked but couldn't find an answer.

I'm having trouble removing the white border on v-expansion-panels when the header is clicked to open. The border is only in the animation

v-expansion-panels when the header is clicked lights up the panel background with a white border. I have an image as my background for the v-expansion-panel background and I don't want to highlight the edge of the component. How can I turn this off?

Transparent buttons on a background image

I have a problem when I put buttons on a background image, for some reason they are transparent and take the color of the background image, if I use the same button component somewhere else that is not on top of a background image the color button is not modified, this only happens when the button is on an image and only in android, someone knows why this happens?
add a TouchebleOpacity on ImageBackground component

UISegmentedControl IOS7 hide border

I am having some graphical issues adapting my app to ios7. All my icons (color icons) now seem worse. They are completelly blue or grey depending where they are set.
Ok, I can assume that. But now, I have some problems with UISegmentedControl. they show a blue thiny line all around and I want to hide it. Just showing the image icon.
Is it possible?