How to set all backgrounds transparent so that you can see the main screen?

I have been thinking about this problem for several days:

How to set all backgrounds to transparency in the application so that you can see the iOS desktop and icons? Is there any method that could help meet demand? (I still do not have the right to a sample image.)

I tried some methods. I view the entire iOS system as a great application. When we open the application on the desktop, it becomes the top "view controller" that will close on the desktop.

With that in mind, I set the instance variable-Window in the AppDelegate class, and the background color of the root view controller is clear. However, there is a black background! .

Can anybody help? You may not have encountered this problem yet, but please think for a few seconds and provide me some ideas.

Thanks in advance!

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2 answers

no, this is impossible to do. If you try to set a clear color for all components of the view, including UIWindow, you will get black color as it arrives.

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This is the solution you can see at vidios WWDC. You have to make a Gaussian Blur, so the first thing you need to do is add a new .m and .h file with the code that I write here, then you need to take and take a picture, use the desired effect and add it to your view, then your UITable UIView or ever should be transparent, you can play with applyBlurWithRadius to archive the desired effect, this call works with any UIImage.

At the end, the color image will be the background, and the other controls above should be transparent.

To do this, you need to add the following libraries:

Acelerate.framework, UIKit.framework, CoreGraphics.framework

I hope you will enjoy.

Happy coding.

  //Screen capture. UIGraphicsBeginImageContext(self.view.bounds.size); CGContextRef c = UIGraphicsGetCurrentContext(); CGContextTranslateCTM(c, 0, 0); [self.view.layer renderInContext:c]; UIImage* viewImage = UIGraphicsGetImageFromCurrentImageContext(); viewImage = [viewImage applyLightEffect]; UIGraphicsEndImageContext(); //.h FILE #import <UIKit/UIKit.h> @interface UIImage (ImageEffects) - (UIImage *)applyLightEffect; - (UIImage *)applyExtraLightEffect; - (UIImage *)applyDarkEffect; - (UIImage *)applyTintEffectWithColor:(UIColor *)tintColor; - (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage; @end //.m FILE #import "cGaussianEffect.h" #import <Accelerate/Accelerate.h> #import <float.h> @implementation UIImage (ImageEffects) - (UIImage *)applyLightEffect { UIColor *tintColor = [UIColor colorWithWhite:1.0 alpha:0.3]; return [self applyBlurWithRadius:1 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil]; } - (UIImage *)applyExtraLightEffect { UIColor *tintColor = [UIColor colorWithWhite:0.97 alpha:0.82]; return [self applyBlurWithRadius:1 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil]; } - (UIImage *)applyDarkEffect { UIColor *tintColor = [UIColor colorWithWhite:0.11 alpha:0.73]; return [self applyBlurWithRadius:1 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil]; } - (UIImage *)applyTintEffectWithColor:(UIColor *)tintColor { const CGFloat EffectColorAlpha = 0.6; UIColor *effectColor = tintColor; int componentCount = CGColorGetNumberOfComponents(tintColor.CGColor); if (componentCount == 2) { CGFloat b; if ([tintColor getWhite:&b alpha:NULL]) { effectColor = [UIColor colorWithWhite:b alpha:EffectColorAlpha]; } } else { CGFloat r, g, b; if ([tintColor getRed:&r green:&g blue:&b alpha:NULL]) { effectColor = [UIColor colorWithRed:r green:g blue:b alpha:EffectColorAlpha]; } } return [self applyBlurWithRadius:10 tintColor:effectColor saturationDeltaFactor:-1.0 maskImage:nil]; } - (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage { if (self.size.width < 1 || self.size.height < 1) { NSLog (@"*** error: invalid size: (%.2f x %.2f). Both dimensions must be >= 1: %@", self.size.width, self.size.height, self); return nil; } if (!self.CGImage) { NSLog (@"*** error: image must be backed by a CGImage: %@", self); return nil; } if (maskImage && !maskImage.CGImage) { NSLog (@"*** error: maskImage must be backed by a CGImage: %@", maskImage); return nil; } CGRect imageRect = { CGPointZero, self.size }; UIImage *effectImage = self; BOOL hasBlur = blurRadius > __FLT_EPSILON__; BOOL hasSaturationChange = fabs(saturationDeltaFactor - 1.) > __FLT_EPSILON__; if (hasBlur || hasSaturationChange) { UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]); CGContextRef effectInContext = UIGraphicsGetCurrentContext(); CGContextScaleCTM(effectInContext, 1.0, -1.0); CGContextTranslateCTM(effectInContext, 0, -self.size.height); CGContextDrawImage(effectInContext, imageRect, self.CGImage); vImage_Buffer effectInBuffer; effectInBuffer.data = CGBitmapContextGetData(effectInContext); effectInBuffer.width = CGBitmapContextGetWidth(effectInContext); effectInBuffer.height = CGBitmapContextGetHeight(effectInContext); effectInBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectInContext); UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]); CGContextRef effectOutContext = UIGraphicsGetCurrentContext(); vImage_Buffer effectOutBuffer; effectOutBuffer.data = CGBitmapContextGetData(effectOutContext); effectOutBuffer.width = CGBitmapContextGetWidth(effectOutContext); effectOutBuffer.height = CGBitmapContextGetHeight(effectOutContext); effectOutBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectOutContext); if (hasBlur) { CGFloat inputRadius = blurRadius * [[UIScreen mainScreen] scale]; NSUInteger radius = floor(inputRadius * 3. * sqrt(2 * M_PI) / 4 + 0.5); if (radius % 2 != 1) { radius += 1; } vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend); vImageBoxConvolve_ARGB8888(&effectOutBuffer, &effectInBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend); vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, radius, radius, 0, kvImageEdgeExtend); } BOOL effectImageBuffersAreSwapped = NO; if (hasSaturationChange) { CGFloat s = saturationDeltaFactor; CGFloat floatingPointSaturationMatrix[] = { 0.0722 + 0.9278 * s, 0.0722 - 0.0722 * s, 0.0722 - 0.0722 * s, 0, 0.7152 - 0.7152 * s, 0.7152 + 0.2848 * s, 0.7152 - 0.7152 * s, 0, 0.2126 - 0.2126 * s, 0.2126 - 0.2126 * s, 0.2126 + 0.7873 * s, 0, 0, 0, 0, 1, }; const int32_t divisor = 256; NSUInteger matrixSize = sizeof(floatingPointSaturationMatrix)/sizeof(floatingPointSaturationMatrix[0]); int16_t saturationMatrix[matrixSize]; for (NSUInteger i = 0; i < matrixSize; ++i) { saturationMatrix[i] = (int16_t)roundf(floatingPointSaturationMatrix[i] * divisor); } if (hasBlur) { vImageMatrixMultiply_ARGB8888(&effectOutBuffer, &effectInBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags); effectImageBuffersAreSwapped = YES; } else { vImageMatrixMultiply_ARGB8888(&effectInBuffer, &effectOutBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags); } } if (!effectImageBuffersAreSwapped) effectImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); if (effectImageBuffersAreSwapped) effectImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); } UIGraphicsBeginImageContextWithOptions(self.size, NO, [[UIScreen mainScreen] scale]); CGContextRef outputContext = UIGraphicsGetCurrentContext(); CGContextScaleCTM(outputContext, 1.0, -1.0); CGContextTranslateCTM(outputContext, 0, -self.size.height); CGContextDrawImage(outputContext, imageRect, self.CGImage); if (hasBlur) { CGContextSaveGState(outputContext); if (maskImage) { CGContextClipToMask(outputContext, imageRect, maskImage.CGImage); } CGContextDrawImage(outputContext, imageRect, effectImage.CGImage); CGContextRestoreGState(outputContext); } if (tintColor) { CGContextSaveGState(outputContext); CGContextSetFillColorWithColor(outputContext, tintColor.CGColor); CGContextFillRect(outputContext, imageRect); CGContextRestoreGState(outputContext); } UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return outputImage; } 
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Source: https://habr.com/ru/post/1495663/


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