iOS繪圓形圖-CGContextAddArc各參數說明

1.使用 UIGraphicsGetCurrentContext() 畫圓

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

x,y爲圓點座標，radius半徑，startAngle爲開始的弧度，endAngle爲 結束的弧度，clockwise 0爲順時針，1爲逆時針。

-(void)drawRect:(CGRect)rect{
    CGFloat lineWidth = 12;
    NSInteger sleepScore = arc4random() % 101;
    //定義一個不透明類型的Quartz 2D繪畫環境,至關於一個畫布
    CGContextRef context = UIGraphicsGetCurrentContext();
    [[UIColor whiteColor] set];
    CGContextFillRect(context, rect);
    //有值圓
    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爲順時針，1爲逆時針
    CGContextDrawPath(context, kCGPathStroke);
    /*寫分數*/
    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;//對齊方式
    attributesDic[NSParagraphStyleAttributeName] = textStyle;
    [text drawInRect:rect withAttributes:attributesDic];
}