计算UILabel文本大小

Sarp Kaya 发表于 Dev

沙普卡亚

我正在UILabels编程绘图。他们从数据库获取大小。所以我不能随便使用sizeToFit。我已经实现了UILabels以通过比例重绘的函数。因此，我需要找到的只是UILabel我认为需要重新绘制最大比例的文本UILabels。所以最后我需要做这样的事情：

    double ratio = 1.00;
    for (UILabel* labels in sec.subviews) {

        float widthLabel = labels.frame.size.width;
        float heightLabel = labels.frame.size.height;
        float heightText = //get the text height here
        float widthText = //get the text width here
        if (widthLabel < widthText) {
            ratio = MAX(widthText/widthLabel,ratio);
        }
        if (heightLabel < heightText) {
            ratio = MAX(heightText/heightLabel, ratio);
        }
    }
    //redraw UILabels with the given ratio here

那么，如何获得文本的高度和宽度大小，因为我的某些文本无法放入标签中，因此我不能简单地使用标签范围？我正在使用Xcode 5和iOS 7。

沙普卡亚

问题所在

CGRect r = [text boundingRectWithSize:CGSizeMake(200, 0)
                              options:NSStringDrawingUsesLineFragmentOrigin
                           attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}
                              context:nil];

是boundingRectWithSize确定CGRect可以具有的最大值。

对于这个问题，我的解决方案是检查它是否超出范围，如果没有超出范围，则文本可以放入标签中。我通过使用循环来做到这一点。

NSString *text = @"This is a long sentence. Wonder how much space is needed?";
CGFloat width = 100;
CGFloat height = 100;
bool sizeFound = false;
while (!sizeFound) {
    NSLog(@"Begin loop");
    CGFloat fontSize = 14;
    CGFloat previousSize = 0.0;
    CGFloat currSize = 0.0;
    for (float fSize = fontSize; fSize < fontSize+6; fSize++) {
        CGRect r = [text boundingRectWithSize:CGSizeMake(width, height)
                                      options:NSStringDrawingUsesLineFragmentOrigin
                                   attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fSize]}
                                      context:nil];
        currSize =r.size.width*r.size.height;
        if (previousSize >= currSize) {
            width = width*11/10;
            height = height*11/10;
            fSize = fontSize+10;
        }
        else {
            previousSize = currSize;
        }
        NSLog(@"fontSize = %f\tbounds = (%f x %f) = %f",
              fSize,
              r.size.width,
              r.size.height,r.size.width*r.size.height);
    }
    if (previousSize == currSize) {
        sizeFound = true;
    }

}
NSLog(@"Size found with width %f and height %f", width, height);

每次迭代后，高度和宽度的大小将增加其值的10％。

我之所以选择6，是因为我不希望标签过于松软。

对于不使用循环的解决方案：

NSString *text = @"This is a long sentence. Wonder how much space is needed?";
CGFloat width = 100;
CGFloat height = 100;

CGFloat currentFontSize = 12;
CGRect r1 = [text boundingRectWithSize:CGSizeMake(width, height)
                              options:NSStringDrawingUsesLineFragmentOrigin
                           attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:currentFontSize+6]}
                              context:nil];

CGRect r2 = [text boundingRectWithSize:CGSizeMake(width, height)
                               options:NSStringDrawingUsesFontLeading
                            attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:currentFontSize+6]}
                               context:nil];

CGFloat firstVal =r1.size.width*r1.size.height;
CGFloat secondVal =r2.size.width*r2.size.height;

NSLog(@"First val %f and second val is %f", firstVal, secondVal);

if (secondVal > firstVal) {
    float initRat = secondVal/firstVal;

    float ratioToBeMult = sqrtf(initRat);

    width *= ratioToBeMult;
    height *= ratioToBeMult;
}

NSLog(@"Final width %f and height %f", width, height);

//for verifying
for (NSNumber *n in @[@(12.0f), @(14.0f), @(17.0f)]) {
    CGFloat fontSize = [n floatValue];
    CGRect r = [text boundingRectWithSize:CGSizeMake(width, height)
                                  options:NSStringDrawingUsesLineFragmentOrigin
                               attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}
                                  context:nil];
    NSLog(@"fontSize = %f\tbounds = (%f x %f) = %f",
          fontSize,
          r.size.width,
          r.size.height,r.size.width*r.size.height);
    firstVal =r.size.width*r.size.height;
}