iOS坐标系的深入探究

UILabel绘制

接着，我们尝试使用CoreText来渲染一段文本。

- (void)drawRect:(CGRect)rect {
 [super drawRect:rect];
 CGContextRef context = UIGraphicsGetCurrentContext();
 NSLog(@"CGContext default matrix %@", NSStringFromCGAffineTransform(CGContextGetCTM(context)));
 NSAttributedString *attrStr = [[NSAttributedString alloc] initWithString:@"测试文本" attributes:@{
             NSForegroundColorAttributeName:[UIColor whiteColor],
             NSFontAttributeName:[UIFont systemFontOfSize:14],
             }];
 CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef) attrStr); // 根据富文本创建排版类CTFramesetterRef
 UIBezierPath * bezierPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, 100, 20)];
 CTFrameRef frameRef = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), bezierPath.CGPath, NULL); // 创建排版数据
 CTFrameDraw(frameRef, context);
}