core-graphics

I would like to draw a circular gradient like in the example picture below. I can manage a radial gradient easily but I am not sure how to do a circular one. I was thinking of drawing a gradient on a line and then transforming it to a circle. Would that be possible? This is how I draw the radial gradient: CGFloat a = MIN(self.frame.size.width, self.frame.size.height) - _lineWidth; //Get current context CGContextRef mainContext = UIGraphicsGetCurrentContext(); CGRect newRect = rect; newRect.origin.x = ((self.frame.size.width - a)/2.0f); newRect.origin.y = ((self.frame.size.height - a)/2.0f);

So far I have looked at using CGContextDrawLinearGradient() and CGContextDrawRadialGradient(), however, with the former I can't figure out how to make the gradient look like a sphere, and with the latter, I can't figure out how to make the gradient into the shape of a sphere, because every time I try, it turns out in the shape of the full cylinder instead of only a sphere. The code I am using to current draw a 2D circle is shown below. I would like to use a gradient or any other method possible using only Core Graphics and/or Quartz 2D to fill the circle in a manner that makes it look like a

I am trying to apply gradient to UIImage using CoreGraphic; however, the result I got is not very nice. I want to create a black to transparent gradient at the bottom of the image to create a contrast for me to place some text. However, the gradient I was able doesn't blend well with the image; you can clearly see the separation in the center . The result I am looking for is like this application: http://capptivate.co/2014/02/17/yummly-3/ How should I apply the gradient to achieve this? ( I have to apply this to large quantity of images ). My Result: Here is my code: func imageWithGradient(img

I am trying to create an app that scales up nicely on the iPhone 4. Currently most of it scales up perfectly, except for one crucial piece: the text that I draw inside a CALayer, inside its drawInContext: method. Here is my code: - (void)drawInContext:(CGContextRef)context { UIGraphicsPushContext(context); CGContextSetGrayFillColor(context, 1.0f, 1.0f); CGContextFillRect(context, self.bounds); CGContextSetAllowsAntialiasing(context, true); CGContextSetShouldAntialias(context, true); CGContextSetAllowsFontSmoothing(context, true); CGContextSetShouldSmoothFonts(context, true);

I need to take an existing pdf file and programmatically fill in a list of form fields with text and then save the pdf without ever displaying it to the user. For instance, if the pdf file contains fields named "LastName", and "FirstName" I would like to set the value of "FirstName" to "Louis" and then save the file. I've been searching for a long time and can't find any guidance on even where to start since the iOS documentation (and most of the questions on here) seem geared towards displaying or creating pdf content instead of modifying it. EDIT: My main question is: Is it possible to open

I have searched this forum, Google and other forums and have not found an the answer to my particular issue. Basically, I have a UIView which contains UITableView . I followed this tutorial and it was partially successful. The problem is the gradient. I have a background image behind the UITableView . So as the cell nears the gradient, I want the background to be showing, instead of the white. I also found this post which which is where I found the tutorial, but I didn't want to hijack that post with my own questions for matt. Any help in the right direction would be great! EDIT1: I know I can

I create a context from an UIImage, and then I draw into it with CGContextDrawImage(bitmapContext, CGRectMake(0, 0, originalImage.size.width, originalImage.size.height), oImageRef); the image appears upside-down due to the flipped coordinate system in quartz. How can I fix that? You should be able to transform the context using something similar to the following: CGContextSaveGState(bitmapContext); CGContextTranslateCTM(bitmapContext, 0.0f, originalImage.size.height); CGContextScaleCTM(bitmapContext, 1.0f, -1.0f); // Draw here CGContextDrawImage(bitmapContext, CGRectMake(0, 0, originalImage