drawRect: inside UIView category - ios

Question

I'm trying to do a UIView category for drawing inside drawRect: method without subclassing. To do this, I created a block to simplify this task.
Here's the code:
UIView+DrawRectBlock.h
#import <UIKit/UIKit.h>
// DrawRect block
typedef void(^DrawRectBlock)(UIView *drawRectView, CGRect rect);
#interface UIView (DrawRectBlock)
- (void)drawInside:(DrawRectBlock)block;
#end
UIView+DrawRectBlock.m
#import "UIView+DrawRectBlock.h"
#import <objc/runtime.h>
#interface UIView ()
#pragma mark - Private properties
#property DrawRectBlock drawBlock;
#end
#implementation UIView (DrawRectBlock)
- (void)drawInside:(DrawRectBlock)block {
if ((self.drawBlock = [block copy])) {
[self setNeedsDisplay];
}
}
- (void)drawRect:(CGRect)rect {
if (self.drawBlock) {
self.drawBlock(self, rect);
}
}
- (void)dealloc {
self.drawBlock = nil;
}
#pragma mark - Others
- (void)setDrawBlock:(DrawRectBlock)drawBlock {
objc_setAssociatedObject(self, #"block", drawBlock, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (DrawRectBlock)drawBlock {
return objc_getAssociatedObject(self, #"block");
}
#end
Finally, I call block as follows:
[_testView drawInside:^(UIView *drawRectView, CGRect rect) {
NSLog(#"DrawReeeeeeect!!!!");
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextSetLineWidth(context, 5.0);
CGContextBeginPath(context);
CGContextMoveToPoint(context, 0.0, 0.0); //start at this point
CGContextAddLineToPoint(context, 100.0, 100.0); //draw to this point
CGContextStrokePath(context);
}];
But "drawRect:" is never called.
Any idea?
Thanks!!

Answer 1

Finally I made a mix of subclass and category and works great!
https://github.com/mhergon/SimpleBlockDrawing