自定义圆形嵌入文字，文字大小自适应

遇到了一个需求，就是在已完成的饼图中嵌入文字或者数字，文字或者数字的大小需要根据饼图圆形的半径自适应大小。查看了一些资料没有找到想要的东西，就自己写了。。。

上代码吧。。。

NSString *str = @"文本";

//设置段落格式
NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
/// Set line break mode
paragraphStyle.lineBreakMode =   NSLineBreakByTruncatingMiddle;
/// Set text alignment
paragraphStyle.alignment = NSTextAlignmentCenter;

//提前给定一个字体的大小并作为一个局部变量，计算出文字或数字的size大小
float currentFontSize=22.0f;

CGSize boudingSize = CGSizeMake(300, 300);
    CGSize requiredSize = CGSizeZero;

UIFont * founda = [UIFont systemFontOfSize:currentFontSize];

NSDictionary *dic = @{NSFontAttributeName:founda,NSParagraphStyleAttributeName: paragraphStyle};

requiredSize = [str boundingRectWithSize:boudingSize options:NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:dic context:nil].size;

//当算出的宽度大于圆形直径时，这时文本就显示不全了，使用while循环改变字体的大小 
//inner_circle_radius 圆形半径
if (requiredSize.width>2*inner_circle_radius) {

        while (requiredSize.width>(2*inner_circle_radius1)) {

          currentFontSize--;

          requiredSize=[str        boundingRectWithSize:boudingSize options:NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:@{NSForegroundColorAttributeName:[UIColor redColor],
                                                                                                                                                                                                    NSFontAttributeName:[UIFont systemFontOfSize:currentFontSize],
                                                                                                                                                                                                               NSParagraphStyleAttributeName: paragraphStyle} context:nil].size;

        }

    }
    //将文本画出
    [str drawInRect:CGRectMake(origin_x-inner_circle_radius1, origin_y-requiredSize.height+10, 2*inner_circle_radius1, requiredSize.height) withAttributes:@{NSForegroundColorAttributeName:[UIColor redColor],
                                                                                                                                                                           NSFontAttributeName:[UIFont systemFontOfSize:currentFontSize],
                                                                                                                                                                           NSParagraphStyleAttributeName: paragraphStyle}];
}

这样就完美解决了。。。

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