你如何复制CALayer？

CALayer *layer = [CALayer layer];

layer.bounds = CGRectMake(0, 0, 100, 100);
layer.position = CGPointMake(100, 100);
layer.backgroundColor = [[UIColor whiteColor] CGColor];
layer.borderColor = [[UIColor blackColor] CGColor];
layer.borderWidth = 2;

[self.view.layer insertSublayer:layer atIndex:0];