// 边框宽度
self.purpleView.layer.borderWidth = 10;
// 边框颜色
self.purpleView.layer.borderColor = [UIColor greenColor].CGColor;
// 圆角
self.purpleView.layer.cornerRadius = 10;
// self.purpleView.layer.masksToBounds = YES;
// 阴影颜色
self.purpleView.layer.shadowColor = [UIColor blueColor].CGColor;
// 阴影偏差
self.purpleView.layer.shadowOffset = CGSizeMake(20, 20);
// 阴影不透明度
self.purpleView.layer.shadowOpacity = 0.5;
// 平移
self.iconView.layer.transform = CATransform3DMakeScale(1.5, 0.5, 0);
// 旋转二维
self.iconView.transform = CGAffineTransformMakeRotation(M_PI_4);
// 旋转三维 方式一
self.iconView.layer.transform = CATransform3DMakeRotation(M_PI_4, 0, 0, 1);
// 旋转三维 方式二
NSValue *value = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(M_PI_4, 0, 0, 1)];
[self.iconView.layer setValue:value forKeyPath:@"transform"];
// 旋转
[self.iconView.layer setValue:@(M_PI_2) forKeyPath:@"transform.rotation"];
self.iconView.layer.transform = CATransform3DMakeScale(0.5, 2, 0);
[self.iconView.layer setValue:[NSValue valueWithCATransform3D:CATransform3DMakeScale(0.5, 2, 0)] forKeyPath:@"transform"];
// 可以传递哪些key path, 在官方文档搜索 "CATransform3D key paths"
[self.iconView.layer setValue:@(-100) forKeyPath:@"transform.translation.x"];
key paths
新建图层
// CALayer *layer = [[CALayer alloc] init];
CALayer *layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0, 0, 100, 100);
layer.position = CGPointMake(200, 100);
layer.cornerRadius = 10;
layer.masksToBounds = YES;
layer.contents = (id)[UIImage imageNamed:@"icon"].CGImage;
[self.view.layer addSublayer:layer];
自定义图层
方式一
继承自CALayer
/**
* 只有明显地调用setNeedsDisplay方法,才会调用drawInContext:方法进行绘制
*/
- (void)drawInContext:(CGContextRef)ctx
{
// 红色
CGContextSetRGBFillColor(ctx, 1, 0, 0, 1);
// 添加圆
CGContextAddEllipseInRect(ctx, CGRectMake(0, 0, 50, 50));
// 实心绘制
CGContextFillPath(ctx);
}
自定义View是这样的
- (void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
// 红色
CGContextSetRGBFillColor(ctx, 1, 0, 0, 1);
// 添加圆
CGContextAddEllipseInRect(ctx, CGRectMake(0, 0, 50, 50));
// 实心绘制
CGContextFillPath(ctx);
}
MyLayer *layer = [MyLayer layer];
layer.bounds = CGRectMake(0, 0, 100, 100);
layer.backgroundColor = [UIColor blueColor].CGColor;
layer.anchorPoint = CGPointZero;
[layer setNeedsDisplay];
[self.view.layer addSublayer:layer];
方式二
CALayer *layer = [CALayer layer];
layer.bounds = CGRectMake(0, 0, 100, 100);
layer.backgroundColor = [UIColor blackColor].CGColor;
layer.anchorPoint = CGPointZero;
layer.position = CGPointMake(100, 100);
layer.delegate = self;
[layer setNeedsDisplay];
[self.view.layer addSublayer:layer];
#pragma mark - 图层的代理方法
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx
{
CGContextSetRGBFillColor(ctx, 1, 0, 0, 1);
CGContextAddRect(ctx, CGRectMake(0, 0, 20, 20));
CGContextFillPath(ctx);
}
view的完整显示过程
- view.layer会准备一个Layer Graphics Contex(图层类型的上下文)
- 调用view.layer.delegate(view)的drawLayer:inContext:,并传入刚才准备好的上下文
- view的drawLayer:inContext:方法内部又会调用view的drawRect:方法
- view就可以在drawRect:方法中实现绘图代码, 所有东西最终都绘制到view.layer上面
- 系统再将view.layer的内容拷贝到屏幕, 于是完成了view的显示
