I have a multiline UILabel whose font size I\'d like to adjust depending on the text length. The whole text should fit into the label\'s frame without truncating it.
Thanks, with that and a little more from someone else I did this custom UILabel, that will respect the minimum font size and there's a bonus option to align the text to top.
h:
@interface EPCLabel : UILabel {
    float originalPointSize;
    CGSize originalSize;
}
@property (nonatomic, readwrite) BOOL alignTextOnTop;
@end
m:
#import "EPCLabel.h"
@implementation EPCLabel
@synthesize alignTextOnTop;
-(void)verticalAlignTop {
    CGSize maximumSize = originalSize;
    NSString *dateString = self.text;
    UIFont *dateFont = self.font;
    CGSize dateStringSize = [dateString sizeWithFont:dateFont 
                                   constrainedToSize:CGSizeMake(self.frame.size.width, maximumSize.height)
                                       lineBreakMode:self.lineBreakMode];
    CGRect dateFrame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width, dateStringSize.height);
    self.frame = dateFrame;
}
- (CGFloat)fontSizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size {
    CGFloat fontSize = [font pointSize];
    CGFloat height = [self.text sizeWithFont:font             
                           constrainedToSize:CGSizeMake(size.width,FLT_MAX)  
                               lineBreakMode:UILineBreakModeWordWrap].height;
    UIFont *newFont = font;
    //Reduce font size while too large, break if no height (empty string)
    while (height > size.height && height != 0 && fontSize > self.minimumFontSize) { 
        fontSize--;  
        newFont = [UIFont fontWithName:font.fontName size:fontSize];   
        height = [self.text sizeWithFont:newFont  
                       constrainedToSize:CGSizeMake(size.width,FLT_MAX) 
                           lineBreakMode:UILineBreakModeWordWrap].height;
    };
    // Loop through words in string and resize to fit
    if (fontSize > self.minimumFontSize) {
        for (NSString *word in [self.text componentsSeparatedByString:@" "]) {
            CGFloat width = [word sizeWithFont:newFont].width;
            while (width > size.width && width != 0 && fontSize > self.minimumFontSize) {
                fontSize--;
                newFont = [UIFont fontWithName:font.fontName size:fontSize];   
                width = [word sizeWithFont:newFont].width;
            }
        }
    }
    return fontSize;
}
-(void)setText:(NSString *)text {
    [super setText:text];
    if (originalSize.height == 0) {
        originalPointSize = self.font.pointSize;
        originalSize = self.frame.size;
    }
    if (self.adjustsFontSizeToFitWidth && self.numberOfLines > 1) {
        UIFont *origFont = [UIFont fontWithName:self.font.fontName size:originalPointSize];
        self.font = [UIFont fontWithName:origFont.fontName size:[self fontSizeWithFont:origFont constrainedToSize:originalSize]];
    }
    if (self.alignTextOnTop) [self verticalAlignTop];
}
-(void)setAlignTextOnTop:(BOOL)flag {
    alignTextOnTop = YES;
    if (alignTextOnTop && self.text != nil)
        [self verticalAlignTop];
}
@end
I hope it helps.