iOS根据字体字号大小和字体label计算label宽度

获取label 大小的方法：

- (CGSize)sizeWithText:(NSString *)text font:(UIFont *)font maxSize:(CGSize)maxSize
{
    NSDictionary *attrs = @{NSFontAttributeName : font};
    return [text boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:attrs context:nil].size;
}

 调用：

-(void)initData
{

    //调用上面的方法，获取 字体的 Size
    CGSize size = [self sizeWithText: @"此处是测试字体" font:[UIFont systemFontOfSize:15] maxSize:CGSizeMake(MAXFLOAT, MAXFLOAT)];
    UILabel * noDataLab = [[UILabel alloc]initWithFrame:CGRectMake(100, 120, size.width, size.height)];
    noDataLab.text = @"此处是测试字体";
    noDataLab.font = FONT(15);
    noDataLab.textColor = [UIColor grayColor];

}