iOS:根据 UILabel 的大小找到正确的字体大小以适合其大小

Question

我有一个 UILabel，其属性 text 我想使用 NSString 设置文本段落。

我有一个数组，其中存储代表文本段落的字符序列。

该段落不必完全适合/包含在这个 UILabel 中。如果该段落没有结束，我将转到下一个标签。

假设我的 UILabel 的矩形大小为 160 X 240，我如何才能确定正确的字体大小以填充 UILabel 的字符串> 里面很好吗？

是否有一种数学方法可以根据屏幕上矩形的大小来计算字体大小？

例如:

UILabel *aLabel = [[UIlabel alloc] initwithFrame(CGRect){{0, 0}, 160, 240}];
aLabel.font = [UIFont fontWithName:@"Courier New" size:<???>]; //(font unit in points)

NSMutableString *aString = [[NSMutableString alloc] init];

//The following tries to fit the character one by one within the label rect based on   
//the width and height of the UILabel by appending String
int index = 0;
for(int x = 0; x < 240; x+=<???>) //height of label (pixel unit)
{
    for(int y = 0; y < 160; y+=<???>) //width of label (pixel unit)
    {
        [aString appendWithString:[paragraphArray objectAtIndex:index]];
        index++;
    }
    [aString appendWithString:@\n"];  //line break
}
aLabel.text = aString;

我怎样才能确定 ??? 的值？是(即 for 循环的字体大小和像素大小)？

如果这不是执行此类任务的最佳方式，请向我建议其他方式。

Answer 1

+(void)resizeFontForLabel:(UILabel*)aLabel{

    // use font from provided label so we don't lose color, style, etc
    UIFont *font = aLabel.font;

    float lblWidth = aLabel.frame.size.width;
    float lblHeight = aLabel.frame.size.height;

    CGFloat fontSize = [font pointSize];
    UIFont *newFont = font;
    TRC_DBG(@"%@", aLabel.text);
    CGFloat height = [aLabel.text sizeWithFont:font constrainedToSize:CGSizeMake(lblWidth,MAXFLOAT) lineBreakMode:aLabel.lineBreakMode].height;

    TRC_DBG(@"Label Height %f Constraint height %f", lblHeight, height);
    //Reduce font size while too large, break if no height (empty string)
    while (height > lblHeight && height != 0) {
        fontSize--;
        newFont = [UIFont fontWithName:font.fontName size:fontSize];
        height = [aLabel.text sizeWithFont:newFont constrainedToSize:CGSizeMake(lblWidth,MAXFLOAT) lineBreakMode:NSLineBreakByWordWrapping].height;
        TRC_DBG(@"Constrained Height %f", height);
    };


    TRC_DBG(@"Font size before adjustment %f", aLabel.font.pointSize);
    // Set the UILabel's font to the newly adjusted font.
    aLabel.font = newFont;
    TRC_DBG(@"Adjust to font size of %f", newFont.pointSize);
    [aLabel setNeedsLayout];
}