iOS自定义UIView绘图 - CAShapeLayers还是drawRect？

Question

I'm new to iOS UIView drawing and I'm really trying to implement a custom UIView class in a standard way.

The UIView class that I'm working on now is simple: it has mostly static background shapes that form a composite shape. I also want to add animation to this UIView class so that a simple shape can animate its path on top of the static shapes.

How I'm currently implementing this

Right now, I'm implementing the static drawing in the drawRect: method of the UIView subclass. This works fine. I also have not implemented animation of the single shape yet.

What I'm looking to have answered

Question 1:

Is it better to have the static shapes drawn in the drawRect: method as I'm currently doing it, or is there a benefit to refactoring all of the shapes being drawn into class-extension-scoped CAShapeLayer properties and doing something like:

-(instancetype) initWithFrame:(CGRect) frame
{
   if (self = [super initWithFrame:frame])
   {
      [self setupView];
   }

   return self;
}

-(void) setupView // Allocate, init, and setup one-time layer properties like fill colorse.
{
   self.shapeLayer1 = [CAShapeLayer layer];
   [self.layer addSubLayer:shapeLayer1];
   self.shapeLayer2 = [CAShapeLayer layer];
   [self.layer addSubLayer:shapeLayer2];
   // ... and so on
}

-(void) layoutSubviews // Set frames and paths of shape layers here.
{
    self.shapeLayer1.frame = self.bounds;
    self.shapeLayer2.frame = self.bounds;

    self.shapeLayer1.path = [UIBezierPath somePath].CGPath;
    self.shapeLayer2.path = [UIBezierPath somePath].CGPath;
}

Question 2: Regardless of whether I implement the static shapes as CAShapeLayers or in drawRect: , is the best way to implement an animatable shape for this UIView a CAShapeLayer property that is implemented as the other CAShapeLayer s would be implemented above? Creating a whole separate UIView class just for one animated shape and adding it as a subview to this view seems silly, so I'm thinking that a CAShapeLayer is the way to go to accomplish that.

I would appreciate any help with this very much!

Answer 1

You could do it either way, but using shape layers for everything would probably be cleaner and faster. Shape layers have built-in animation support using Core Animation.

It's typically faster to avoid implementing drawRect and instead let the system draw for you.