The following blog post is where I got my answer when I had issues with modifying and saving Exif data Caffeinated Cocoa. This works on iOS. Here is my test code for writing Exif and GPS data. It pretty much a copy and paste of the code from the above blog. I am using this … Read more
The documentation on the use of the bridge keyword can be found here. Specifically, I want to point out ยง3.2.4: (__bridge T) op casts the operand to the destination type T. If T is a retainable object pointer type, then op must have a non-retainable pointer type. If T is a non-retainable pointer type, then … Read more
If I understand your question correctly, there is a simple solution to this. During your long-running routine you need to tell the current runloop to process for a single iteration (or more, of the runloop) at certain points in your own processing. e.g, when you want to update the display. Any views with dirty update … Read more
Using CGImageDestination and passing kUTTypePNG is the correct approach. Here’s a quick snippet: @import MobileCoreServices; // or `@import CoreServices;` on Mac @import ImageIO; BOOL CGImageWriteToFile(CGImageRef image, NSString *path) { CFURLRef url = (__bridge CFURLRef)[NSURL fileURLWithPath:path]; CGImageDestinationRef destination = CGImageDestinationCreateWithURL(url, kUTTypePNG, 1, NULL); if (!destination) { NSLog(@”Failed to create CGImageDestination for %@”, path); return NO; } … Read more
From the docs: The constants for specifying the alpha channel information are declared with the CGImageAlphaInfo type but can be passed to this parameter safely. So you can just use a cast to suppress the warning: CGBitmapInfo bitmapInfo = (CGBitmapInfo) kBitmapInfo;
A rotation of angle a around the point (x,y) corresponds to the affine transformation: CGAffineTransform transform = CGAffineTransformMake(cos(a),sin(a),-sin(a),cos(a),x-x*cos(a)+y*sin(a),y-x*sin(a)-y*cos(a)); You may need to plug in -a instead of a depending on whether you want the rotation to be clockwise or counterclockwise. Also, you may need to plug in -y instead of y depending on whether or … Read more
Core Graphics does not allow for the setting of a global color table, just a local color table for a single-image GIF file. Multi-image gif files require individual properties of each image to be set, which means the kCGImagePropertyGIFImageColorMap will have no effect when the source images are not themselves GIF files, and the code … Read more
After much digging around, I’ve found you can set a symbolic breakpoint on “CGPostError” in Xcode, and that will give you a stack trace.
I think that it’s easiest to explain what is happening for each of the three locations and then a “conclusion” at the end. I’m also adding some illustrations, showing exactly the behaviour that you are mentioning in your question so that it will be easier to follow for someone who hasn’t tried these three things … Read more
I guess you’re filling up the queue (underlying mach port)… You can confirm this using the “scheduling” or “system call” instrument in Instruments. (Create a new blank document, add the instrument, then under File > Record Options… make sure “deferred mode” is checked.) This will show all thread activity in your app (when threads block, … Read more