开发当中总会遇到字体小看不清楚的情况，我这里做了一个放大镜的功能。直接上代码：

- (void)setPointToMagnify:(CGPoint)pointToMagnify

{

_pointToMagnify = pointToMagnify;

CGPoint center = CGPointMake(pointToMagnify.x, self.center.y);

if (pointToMagnify.y > CGRectGetHeight(self.bounds) * 0.5) {

center.y = pointToMagnify.y -  CGRectGetHeight(self.bounds) / 2;

}

self.center = center;

[self.contentLayer setNeedsDisplay];

}

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx

{

CGContextTranslateCTM(ctx, self.frame.size.width * 0.5, self.frame.size.height * 0.5);

CGContextScaleCTM(ctx, 1.2, 1.2);

CGContextTranslateCTM(ctx, -1 * self.pointToMagnify.x, -1 * self.pointToMagnify.y);

[self.viewToMagnify.layer renderInContext:ctx];

}