iOS 生成本地验证码

在应用程序注册、登陆或者有关支付确认的界面，经常会用到验证码，验证码有的是通过手机发送获取的，有的是在本地点击获取的，通过手机发送获取的动态验证码可以使用第三方类库实现，本地点击获取的是在本地自己绘制的，下面我们来详细讲解一下本地生成动态验证码的过程。

导入CoreGraphics.framework

验证码封装了一个UIView，在使用的时候直接把这个View加到界面上使用

CaptchaView.h

#import <UIKit/UIKit.h>    @interface CaptchaView : UIView    @property (nonatomic, retain) NSArray *changeArray; //字符素材数组  @property (nonatomic, retain) NSMutableString *changeString;  //验证码的字符串    @end

CaptchaView.m

#import "CaptchaView.h"    #define kRandomColor  [UIColor colorWithRed:arc4random() % 256 / 256.0 green:arc4random() % 256 / 256.0 blue:arc4random() % 256 / 256.0 alpha:1.0];  #define kLineCount 6  #define kLineWidth 1.0  #define kCharCount 6  #define kFontSize [UIFont systemFontOfSize:arc4random() % 5 + 15]    @implementation CaptchaView  @synthesize changeString,changeArray;    - (instancetype)initWithFrame:(CGRect)frame  {      if (self = [super initWithFrame:frame]) {            self.layer.cornerRadius = 5.0; //设置layer圆角半径          self.layer.masksToBounds = YES; //隐藏边界          self.backgroundColor = kRandomColor;            //显示一个随机验证码          [self changeCaptcha];      }        return self;  }  #pragma mark 更换验证码,得到更换的验证码的字符串  -(void)changeCaptcha  {  //<一>从字符数组中随机抽取相应数量的字符，组成验证码字符串      //数组中存放的是全部可选的字符，可以是字母，也可以是中文      self.changeArray = [[NSArray alloc] initWithObjects:@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"A",@"B",@"C",@"D",@"E",@"F",@"G",@"H",@"I",@"J",@"K",@"L",@"M",@"N",@"O",@"P",@"Q",@"R",@"S",@"T",@"U",@"V",@"W",@"X",@"Y",@"Z",@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i",@"j",@"k",@"l",@"m",@"n",@"o",@"p",@"q",@"r",@"s",@"t",@"u",@"v",@"w",@"x",@"y",@"z",@"杰",@"瑞",@"教",@"育",nil];        //如果能确定最大需要的容量，使用initWithCapacity:来设置，好处是当元素个数不超过容量时，添加元素不需要重新分配内存      NSMutableString *getStr = [[NSMutableString alloc] initWithCapacity:kCharCount];      self.changeString = [[NSMutableString alloc] initWithCapacity:kCharCount];        //随机从数组中选取需要个数的字符，然后拼接为一个字符串      for(int i = 0; i < kCharCount; i++)      {          NSInteger index = arc4random() % ([self.changeArray count] - 1);          getStr = [self.changeArray objectAtIndex:index];            self.changeString = (NSMutableString *)[self.changeString stringByAppendingString:getStr];      }    //<2>从网络获取字符串，然后把得到的字符串在本地绘制出来（网络获取步骤在这省略）  //    self.changeString = [NSMutableString stringWithString:@"杰瑞教育"];  }    #pragma mark 点击view时调用，因为当前类自身就是UIView，点击更换验证码可以直接写到这个方法中，不用再额外添加手势  -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event  {      //点击界面，切换验证码      [self changeCaptcha];        //setNeedsDisplay调用drawRect方法来实现view的绘制      [self setNeedsDisplay];  }    #pragma mark 绘制界面（1.UIView初始化后自动调用； 2.调用setNeedsDisplay方法时会自动调用）  - (void)drawRect:(CGRect)rect {      // 重写父类方法，首先要调用父类的方法      [super drawRect:rect];        //设置随机背景颜色      self.backgroundColor = kRandomColor;        //获得要显示验证码字符串，根据长度，计算每个字符显示的大概位置      NSString *text = [NSString stringWithFormat:@"%@",self.changeString];      CGSize cSize = [@"S" sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:20]}]; int width = rect.size.width / text.length - cSize.width;      int height = rect.size.height - cSize.height;      CGPoint point;        //依次绘制每一个字符,可以设置显示的每个字符的字体大小、颜色、样式等      float pX, pY;      for (int i = 0; i < text.length; i++)      {          pX = arc4random() % width + rect.size.width / text.length * i;          pY = arc4random() % height;          point = CGPointMake(pX, pY);          unichar c = [text characterAtIndex:i];          NSString *textC = [NSString stringWithFormat:@"%C", c];            [textC drawAtPoint:point withAttributes:@{NSFontAttributeName:kFontSize}];      }        //调用drawRect：之前，系统会向栈中压入一个CGContextRef，调用UIGraphicsGetCurrentContext()会取栈顶的CGContextRef      CGContextRef context = UIGraphicsGetCurrentContext();      //设置画线宽度      CGContextSetLineWidth(context, kLineWidth);        //绘制干扰的彩色直线      for(int i = 0; i < kLineCount; i++)      {          //设置线的随机颜色          UIColor *color = kRandomColor;          CGContextSetStrokeColorWithColor(context, [color CGColor]);          //设置线的起点          pX = arc4random() % (int)rect.size.width;          pY = arc4random() % (int)rect.size.height;          CGContextMoveToPoint(context, pX, pY);          //设置线终点          pX = arc4random() % (int)rect.size.width;          pY = arc4random() % (int)rect.size.height;          CGContextAddLineToPoint(context, pX, pY);          //画线          CGContextStrokePath(context);      }  }    @end

<三>在界面上添加验证码

ViewController.m

#import "ViewController.h"  #import "CaptchaView.h"    @interface ViewController ()<UITextFieldDelegate,UIAlertViewDelegate>  {      CaptchaView *_captchaView;      UITextField *_input;  }    @end    @implementation ViewController    - (void)viewDidLoad {      [super viewDidLoad];        //显示验证码界面      _captchaView = [[CaptchaView alloc] initWithFrame:CGRectMake(20, 40, 150, 40)];      [self.view addSubview:_captchaView];        //提示文字      UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(190, 40, 100, 40)];      label.text = @"点击图片换验证码";      label.font = [UIFont systemFontOfSize:12];      label.textColor = [UIColor grayColor];      [self.view addSubview:label];        //添加输入框      _input = [[UITextField alloc] initWithFrame:CGRectMake(20, 100, 150, 40)];      _input.layer.borderColor = [UIColor lightGrayColor].CGColor;      _input.layer.borderWidth = 2.0;      _input.layer.cornerRadius = 5.0;      _input.font = [UIFont systemFontOfSize:21];      _input.placeholder = @"请输入验证码!";      _input.clearButtonMode = UITextFieldViewModeWhileEditing;      _input.backgroundColor = [UIColor clearColor];      _input.textAlignment = NSTextAlignmentCenter;      _input.returnKeyType = UIReturnKeyDone;      _input.delegate = self;      [self.view addSubview:_input];  }    #pragma mark 输入框协议中方法,点击return按钮  - (BOOL)textFieldShouldReturn:(UITextField *)textField  {      //判断输入的是否为验证图片显示的验证码      if ([_input.text isEqualToString:_captchaView.changeString]) {          //正确弹出警告款提示正确          UIAlertView *alview = [[UIAlertView alloc] initWithTitle:@"恭喜您 ^o^" message:@"验证成功" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];          [alview show];      }      else      {          //验证不匹配，验证码和输入框晃动          CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"transform.translation.x"];          anim.repeatCount = 1;          anim.values = @[@-20, @20, @-20];          [_captchaView.layer addAnimation:anim forKey:nil];          [_input.layer addAnimation:anim forKey:nil];      }      return YES;  }    #pragma mark 警告框中方法  -(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex  {      //清空输入框内容，收回键盘      if (buttonIndex==0) {          _input.text = @"";          [_input resignFirstResponder];      }  }  @end