ios - 创建自定义 CALayer 实现

Question

我正在尝试学习 Core Animation 来开发某个应用程序，但我需要继承 CALayer 类，但是我正在努力让图层自行绘制。

我需要自定义 CALayer 来拥有一些额外的属性并处理自定义事件(触摸等)，但是从一开始我正在实现的基本 CALayer 并没有绘制它自己，谁能告诉我我做错了什么？

我有一个 魔方

#import "MagicSquare.h"

@implementation MagicSquare


-(id) initWithLayer:(id)layer {
    self = [super initWithLayer:layer];


    self.bounds = CGRectMake(0, 0, 200, 200);
    self.position = CGPointMake(10,10);
    self.cornerRadius = 100;
    self.borderColor = [UIColor redColor].CGColor;
    self.borderWidth = 1.5;

    return self;
}

- (void)drawInContext:(CGContextRef)theContext
{

    NSLog(@"Drawing");
    CGMutablePathRef thePath = CGPathCreateMutable();

    CGPathMoveToPoint(thePath,NULL,15.0f,15.f);
    CGPathAddCurveToPoint(thePath,
                          NULL,
                          15.f,250.0f,
                          295.0f,250.0f,
                          295.0f,15.0f);

    CGContextBeginPath(theContext);
    CGContextAddPath(theContext, thePath );

    CGContextSetLineWidth(theContext,
                          1.0);
    CGContextSetStrokeColorWithColor(theContext,
                                     [UIColor redColor].CGColor);
    CGContextStrokePath(theContext);
    CFRelease(thePath);
}

下面是我试图让它在主 Controller 上绘制的方法

@implementation BIDViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    MagicSquare *layer = [[MagicSquare alloc] initWithLayer:[CALayer layer]];

    [self.view.layer addSublayer:layer];

}

Answer 1

找到问题了。

我需要在图层上调用 setNeedsDisplay，因为它不会自动绘制:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    MagicSquare *layer = [[MagicSquare alloc] initWithLayer:[CALayer layer]];

    [self.view.layer addSublayer:layer];

    [layer setNeedsDisplay];
}