设置UIView为圆角矩形

一、直接设置（已通过测试）

必须先导入头文件。

#import <QuartzCore/QuartzCore.h>

...

bgView.layer.cornerRadius = cornerRadiusInPixels;

bgView.layer.masksToBounds = YES;

bgView.opaque = NO;

二、在drawRect里画（未测试）

...

CGFloat radius = 20.0;

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1);

CGFloat minx = CGRectGetMinX(rect), midx = CGRectGetMidX(rect), maxx = CGRectGetMaxX(rect);

CGFloat miny = CGRectGetMinY(rect), midy = CGRectGetMidY(rect), maxy = CGRectGetMaxY(rect);

CGContextMoveToPoint(context, minx, midy);

CGContextAddArcToPoint(context, minx, miny, midx, miny, radius);

CGContextAddArcToPoint(context, maxx, miny, maxx, midy, radius);

CGContextAddArcToPoint(context, maxx, maxy, midx, maxy, radius);

CGContextAddArcToPoint(context, minx, maxy, minx, midy, radius);

CGContextClosePath(context);

CGContextDrawPath(context, kCGPathFill);