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];}