1.使用 UIGraphicsGetCurrentContext() 画圆

CGContextAddArc(<#CGContextRef  _Nullable c#>, <#CGFloat x#>, <#CGFloat y#>, <#CGFloat radius#>, <#CGFloat startAngle#>, <#CGFloat endAngle#>, <#int clockwise#>)

x,y为圆点坐标，radius半径，startAngle为开始的弧度，endAngle为 结束的弧度，clockwise 0为顺时针，1为逆时针。

-(void)drawRect:(CGRect)rect{CGFloat lineWidth = 12;NSInteger sleepScore = arc4random() % 101;//定义一个不透明类型的Quartz 2D绘画环境,相当于一个画布CGContextRef context = UIGraphicsGetCurrentContext();[[UIColor whiteColor] set];CGContextFillRect(context, rect);//有值圆CGFloat scoreLine = sleepScore/100.0;Log(@"sleepScore %ld %f",sleepScore,scoreLine);CGContextSetStrokeColorWithColor(context, [UIColor colorWithHexString:@"#48BBAD"].CGColor);CGContextSetLineWidth(context, lineWidth);CGContextAddArc(context, rect.size.width/2,rect.size.height, rect.size.width/2-lineWidth/2, -M_PI, -M_PI/4, 0);// 0为顺时针，1为逆时针CGContextDrawPath(context, kCGPathStroke);/*写分数*/CGFloat fontSize = (rect.size.height-lineWidth)*0.7;CGRect scoreRect = CGRectMake(rect.size.width/2-fontSize, rect.size.height-fontSize, fontSize*2, fontSize);[self drawTextWithContent:@"100" WithFontSize:fontSize WithWeight:1 withTextColor:[UIColor blackColor] withRect:scoreRect withAlignment:NSTextAlignmentCenter];
}
-(void)drawTextWithContent:(NSString *)text WithFontSize:(CGFloat)fontSize WithWeight:(CGFloat)weight withTextColor:(UIColor *)textColor withRect:(CGRect)rect withAlignment:(NSTextAlignment)alignment{//    Log(@"fontSize:%f",fontSize);NSMutableDictionary *attributesDic = [NSMutableDictionary dictionary];attributesDic[NSFontAttributeName] = [UIFont systemFontOfSize:fontSize weight:weight];attributesDic[NSForegroundColorAttributeName] = textColor;//段落格式NSMutableParagraphStyle *textStyle = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];textStyle.lineBreakMode = NSLineBreakByWordWrapping;textStyle.alignment = alignment;//对齐方式attributesDic[NSParagraphStyleAttributeName] = textStyle;[text drawInRect:rect withAttributes:attributesDic];
}