Under what circumstances will a CGBitmapContext fail to allocate? I have a table view, and it has multiple view options. The user can see a small table cell with just previews, one larger preview p...

I have the following code: let ref:CGContextRef = CGBitmapContextCreate(nil , 200, 130, CGImageGetBitsPerComponent(self.CGImage), 0, CGImageGetColorSpace(self.CGImage), CGImageGetBitmapInfo(self.C...

In my application I need to resize and crop some images, stored locally and online. I am using Trevor Harmon's tutorial which implements UIImage+Resize. On my iPhone 4(iOS 4.3.1) everything works ...

I just updated Xcode from version 4.6.2 to 5.0, and after doing a method in my project (created in Xcode 4.6.2) is suddenly giving a compiler warning. I have tried re-opening the project in both th...

Apple tech note QA1037 says "To create an alpha-only bitmap context simply pass NULL for the colorspace parameter." However, I am not sure what to pass for the bitmapInfo parameter. I was trying...

Is it true that if it is in UIKit, including drawRect, the HD aspect of Retina display is automatically handled? So does that mean in drawRect, the current graphics context for a 1024 x 768 view is...

I am facing a crash with following error: "CGDataProviderCreateWithCopyOfData: vm_copy failed: status 1." I have multiple questions and you can help. What does status 1 stand for in vm_copy ...

My original question: I'm creating a simple drawing application and need to be able to draw over existing, previously drawn content in my drawRect. What is the proper way to draw on top of ex...

I desperately need to create a CGContextRef WITHOUT an alpha channel. Unfortunately, with Core Graphics you CANNOT specify kCGImageAlphaNone with CGBitmapCreateContext. Can someone PLEASE post a w...

I have a PNG image that has an unsupported bitmap graphics context pixel format. Whenever I attempt to resize the image, CGBitmapContextCreate() chokes on the unsupported format I receive the fol...

First, check out this very handy extension to CALayer from elsewhere on SO. It helps you determine if a point in a layer's contents-assigned CGImageRef is or isn't transparent. n.b.: There is no g...

Alright I am having a world of difficulty tracking down this memory leak. When running this script I do not see any memory leaking, but my objectalloc is climbing. Instruments points to CGBitmapCon...