objective c查找字符串的像素宽度

Question

我有一个固定宽度的UIButton，我想在其中放置文字。由于String的大小事先是未知的，因此当我从平面文件中读取字符串时，我将不得不调整字体大小。我怎样才能做到这一点？类似于以下的功能将很棒：

UIFont resizeFontAs:(UIFont)initialFont andStringAs:(NSString*)string andWidthAs:(int)width

提前致谢

编辑：此代码似乎不起作用：

// Method for creating button, with background image and other properties
- (UIButton *) getCallAgentButtonWithTitleAs:(NSString *)aTitle andImageAs:(UIImage*)bgImg atIndex:(int)index{    
    UIButton *aButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];  
    aButton.frame = CGRectMake(10, 2+index*50, 300, 48);    
    aButton.titleLabel.frame = CGRectMake(aButton.titleLabel.frame.origin.x + 25.0,                   aButton.titleLabel.frame.origin.y, aButton.titleLabel.frame.size.width - 50.0,     aButton.titleLabel.frame.size.height);     
    aButton.titleLabel.adjustsFontSizeToFitWidth = YES;
    [aButton setTitle:aTitle forState:UIControlStateNormal];
    //aButton.titleLabel.font = [UIFont boldSystemFontOfSize:12];   
    [aButton setTitleColor:UIColorFromRGB(0xFDD428) forState:UIControlStateNormal];
    [aButton setBackgroundImage:bgImg forState:UIControlStateNormal];
    [aButton addTarget:self action:@selector(callAgent:) forControlEvents:UIControlEventTouchUpInside];
    // set the tag as the index and use it later to obtain the phoneNo
    [aButton setTag:index];
    return aButton;  
}

Answer 1

您可以告诉按钮的标签调整字体本身的大小。

myButton.titleLabel.adjustsFontSizeToFitWidth = YES;
myButton.titleLabel.minimumFontSize = 6.0; // Pick your own value here.

Answer 2

使用以下方法：

-  (CGSize)sizeWithFont:(UIFont *)font
            minFontSize:(CGFloat)minFontSize
         actualFontSize:(CGFloat *)actualFontSize
               forWidth:(CGFloat)width
          lineBreakMode:(UILineBreakMode)lineBreakMode

这将允许您指定默认大小（第一个arg）和最小大小，并且必要时将自动缩放字体。