详解UILabel的adjustsFontSizeToFitWidth值

UILabel有一个属性值，叫adjustsFontSizeToFitWidth，看着名字就知道，他是用来让文字自动适应UILabel宽度的。

先看看显示效果：

测试用源码：

////  RootViewController.m//  Letters////  Created by YouXianMing on 14-9-14.//  Copyright (c) 2014年 YouXianMing. All rights reserved.//#import "RootViewController.h"@interface RootViewController ()@end@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];    {        UILabel *label                  = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 250, 30)];        label.layer.borderWidth         = 1.f;        CGPoint point                   = self.view.center;        point.y                         = 70;        label.center                    = point;        label.text                      = @"YouXianMing NoZuoNoDie";        label.textAlignment             = NSTextAlignmentCenter;        label.adjustsFontSizeToFitWidth = YES;        label.baselineAdjustment        = UIBaselineAdjustmentAlignCenters;        [self.view addSubview:label];    }        {        UILabel *label                  = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 200, 30)];        label.layer.borderWidth         = 1.f;        CGPoint point                   = self.view.center;        point.y                         = 120;        label.center                    = point;        label.text                      = @"YouXianMing NoZuoNoDie";        label.textAlignment             = NSTextAlignmentCenter;        label.adjustsFontSizeToFitWidth = YES;        label.baselineAdjustment        = UIBaselineAdjustmentAlignCenters;        [self.view addSubview:label];    }        {        UILabel *label                  = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 150, 30)];        label.layer.borderWidth         = 1.f;        CGPoint point                   = self.view.center;        point.y                         = 170;        label.center                    = point;        label.text                      = @"YouXianMing NoZuoNoDie";        label.textAlignment             = NSTextAlignmentCenter;        label.adjustsFontSizeToFitWidth = YES;        label.baselineAdjustment        = UIBaselineAdjustmentAlignCenters;        [self.view addSubview:label];    }        {        UILabel *label                  = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100, 30)];        label.layer.borderWidth         = 1.f;        CGPoint point                   = self.view.center;        point.y                         = 220;        label.center                    = point;        label.text                      = @"YouXianMing NoZuoNoDie";        label.textAlignment             = NSTextAlignmentCenter;        label.adjustsFontSizeToFitWidth = YES;        label.baselineAdjustment        = UIBaselineAdjustmentAlignCenters;        [self.view addSubview:label];    }}@end

以下是核心代码：