UPDATE I’ve posted a Swift version of this answer separately. ORIGINAL This is a fun little problem. First of all, there are lots of ways to draw arrows, with curved or straight sides. Let’s pick a very simple way and label the measurements we’ll need: We want to write a function that takes the start … Read more
As the developer of an iPhone application which does just that, trust me when I say typesetting equations is not a trivial undertaking. In my case, I used Core Animation layers to construct the sub-elements of a parsed equation. The equations are constructed hierarchically, and the operations that compose them are laid out as such. … Read more
Something like this might help you get started: NSURL *documentURL = …; // URL to file or http resource etc. CGPDFDocumentRef pdfDocument = CGPDFDocumentCreateWithURL((CFURLRef)documentURL); CGPDFDictionaryRef pdfDocDictionary = CGPDFDocumentGetCatalog(pdfDocument); // loop through dictionary… CGPDFDictionaryApplyFunction(pdfDocDictionary, ListDictionaryObjects, NULL); CGPDFDocumentRelease(pdfDocument); … void ListDictionaryObjects (const char *key, CGPDFObjectRef object, void *info) { NSLog(“key: %s”, key); CGPDFObjectType type = CGPDFObjectGetType(object); switch … Read more
Check UIBezierPath setLineDash:count:phase: method: – (void)setLineDash:(const CGFloat *)pattern count:(NSInteger)count phase:(CGFloat)phase` method. This allows you to draw dashed lines. First add a CAShapeLayer. Add it as sublayer to your UIView. It has a path property. Now make an object of UIBezierPath. Draw the line using setLineDash. For example: UIBezierPath *path = [UIBezierPath bezierPath]; //draw a line … Read more
Solution using Modulo A simple solution that catches all cases. degrees = (degrees + 360) % 360; // +360 for implementations where mod returns negative numbers Explanation Positive: 1 to 180 If you mod any positive number between 1 and 180 by 360, you will get the exact same number you put in. Mod here … Read more
CGAffineTransformMakeRotation expects angle in radians, not in degrees. #define DEGREES_TO_RADIANS(x) (M_PI * (x) / 180.0) … CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(45));
I adapted Apple’s CoreTextArcCocoa sample project (mentioned by Tom H in this reply) and thought I’d share it here. I added a few other features as well, such as the ability to set the arc size to something smaller than 180, and the text color and offset shift as properties (so that you don’t have … Read more