Creating a Core Graphics Context
suggest changeCore Graphics context
A Core Graphics context is a canvas which we can draw in it and set some properties like the line thickness.
Making a context
To make a context, we use the UIGraphicsBeginImageContextWithOptions()
C function. Then, when we are done with drawing, we just call UIGraphicsEndImageContext()
to end the context:
Swift
let size = CGSize(width: 256, height: 256)
UIGraphicsBeginImageContextWithOptions(size, false, 0)
let context = UIGraphicsGetCurrentContext()
// drawing code here
UIGraphicsEndImageContext()
Objective-C
CGSize size = [CGSize width:256 height:256];
UIGraphicsBeginImageContextWithOptions(size, NO, 0);
CGContext *context = UIGraphicsGetCurrentContext();
// drawing code here
UIGraphicsEndImageContext();
In the code above, we passed 3 parameters to the UIGraphicsBeginImageContextWithOptions()
function:
- A
CGSize
object which stores the whole size of the context (the canvas) - A boolean value which if it is true, the context will be opaque
- An integer value which sets the scale (1 for non-retina, 2 for retina and 3 for retina HD screens). If set to 0, the system automatically handles the scale based on the target device.
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