How to Create a Colored 1X1 Uiimage on the iPhone Dynamically

How to create a colored 1x1 UIImage on the iPhone dynamically?

You can use CGContextSetFillColorWithColor and CGContextFillRect for this:

Swift

extension UIImage {
    class func image(with color: UIColor) -> UIImage {
        let rect = CGRectMake(0.0, 0.0, 1.0, 1.0)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()

        CGContextSetFillColorWithColor(context, color.CGColor)
        CGContextFillRect(context, rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return image
    }
}

Swift3

extension UIImage {
    class func image(with color: UIColor) -> UIImage {
        let rect = CGRect(origin: CGPoint(x: 0, y:0), size: CGSize(width: 1, height: 1))
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()!

        context.setFillColor(color.cgColor)
        context.fill(rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return image!
    }
}

Objective-C

+ (UIImage *)imageWithColor:(UIColor *)color {
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

Trying to create a colored circle UIImage, but it always ends up square. Why?

The newer way is to use UIGraphicsImageRenderer which gives you the correct point scale automatically. Also a path can fill itself so there is no need for a clipping mask:

func circleFromColor(_ color: UIColor, size: CGSize = CGSize(width: 1.0, height: 1.0)) -> UIImage? {
  UIGraphicsImageRenderer(size: size).image { context in
    color.setFill()
    UIBezierPath(ovalIn: .init(origin: .zero, size: size)).fill()
  }
}

Here is how you do it the old way:

func circleFromColor(_ color: UIColor, size: CGSize = CGSize(width: 1.0, height: 1.0)) -> UIImage? {
    let rect = CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height)
    UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)

    guard let context = UIGraphicsGetCurrentContext() else { return nil }

    context.setFillColor(color.cgColor)

    let radius: CGFloat = 8.0 * UIScreen.main.scale
    let maskPath = UIBezierPath(roundedRect: rect, byRoundingCorners: .allCorners, cornerRadii: CGSize(width: radius, height: radius))
    maskPath.addClip()
    maskPath.fill()

    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return image
}

How to create a UIImage programmatically with contents

This will help you

UIImage *image1 = [UIImage imageNamed:@"image1.png"]; 
UIImage *image2 = [UIImage imageNamed:@"image2.png"]; 

CGSize newSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext( newSize );

[image1 drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

[image2 drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.8];
UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

How to create UIImage object by url(swfit?)

A method that get image from url

func getImageWithURL(urlString:String,completion: @escaping (_ image:UIImage?) -> Void) {
        guard let url = URL(string: urlString) else {
            print("invalid url")
            completion(nil)
            return
        }
        DispatchQueue.global().async {
            if let data = try? Data(contentsOf: url) {
                DispatchQueue.main.async {
                    let image = UIImage(data: data)
                    completion(image)
                }
            } else {
                print("Error: Url not conataining Image")
                completion(nil)
            }
        }
    }

and how you can call it

 getImageWithURL(urlString: "https://picsum.photos/200") { image in
        if let image = image {
            print("there is an image")
            let pngData = image.pngData()
            let jpegData = image.jpegData(compressionQuality: 1.0)
        }
    }

Create UIImage with solid color in Swift

Another nice solution,
Swift 3.0

    public extension UIImage {
      convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
        let rect = CGRect(origin: .zero, size: size)
        UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
        color.setFill()
        UIRectFill(rect)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        guard let cgImage = image?.cgImage else { return nil }
        self.init(cgImage: cgImage)
      }
    }

Swift 2.2 compatible, is to create another constructor in UIImage, in this way:

    public extension UIImage {
        public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
            let rect = CGRect(origin: .zero, size: size)
            UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
            color.setFill()
            UIRectFill(rect)
            let image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
        
            guard let cgImage = image?.CGImage else { return nil }
            self.init(CGImage: cgImage)
        }  
    }

In this way you can create the custom colored-image in this way:

    let redImage = UIImage(color: .redColor())

Or, optionally, create the image with a custom size:

    let redImage200x200 = UIImage(color: .redColor(), size: CGSize(width: 200, height: 200))

Creating UIImage programmatically from UIView

+ (UIImage *)imageWithColor:(UIColor *)color andRect:(CGRect)rect {
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

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