How to create a black UIImage?

Question

I\'ve looked around everywhere, but I can\'t find a way to do this. I need to create a black UIImage of a certain width and height (The width and height change, so I can\'t just

Answer 1

Like this

let image = UIGraphicsImageRenderer(size: bounds.size).image { _ in
      UIColor.black.setFill()
      UIRectFill(bounds)
}

As quoted in this WWDC vid

There's another function that's older; UIGraphicsBeginImageContext. But please, don't use that.

Answer 2

Depending on your situation, you could probably just use a UIView with its backgroundColor set to [UIColor blackColor]. Also, if the image is solidly-colored, you don't need an image that's actually the dimensions you want to display it at; you can just scale a 1x1 pixel image to fill the necessary space (e.g., by setting the contentMode of a UIImageView to UIViewContentModeScaleToFill).

Having said that, it may be instructive to see how to actually generate such an image:

CGSize imageSize = CGSizeMake(64, 64);
UIColor *fillColor = [UIColor blackColor];
UIGraphicsBeginImageContextWithOptions(imageSize, YES, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
[fillColor setFill];
CGContextFillRect(context, CGRectMake(0, 0, imageSize.width, imageSize.height));
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Answer 3

Swift 3:

func uiImage(from color:UIColor?, size:CGSize) -> UIImage? {

    UIGraphicsBeginImageContextWithOptions(size, true, 0)
    defer {
        UIGraphicsEndImageContext()
    }

    let context = UIGraphicsGetCurrentContext()
    color?.setFill()
    context?.fill(CGRect.init(x: 0, y: 0, width: size.width, height: size.height))
    return UIGraphicsGetImageFromCurrentImageContext()
}

Answer 4

Here is an example that creates a black UIImage that is 1920x1080 by creating it from a CGImage created from a CIImage:

let frame = CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: 1920, height: 1080))
let cgImage = CIContext().createCGImage(CIImage(color: .black()), from: frame)!
let uiImage = UIImage(cgImage: cgImage)

Answer 5

UIGraphicsBeginImageContextWithOptions(CGSizeMake(w,h), NO, 0);
UIBezierPath* p =
    [UIBezierPath bezierPathWithRect:CGRectMake(0,0,w,h)];
[[UIColor blackColor] setFill];
[p fill];
UIImage* im = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Now im is the image.

That code comes almost unchanged from this section of my book: http://www.apeth.com/iOSBook/ch15.html#_graphics_contexts