在應用程序注冊、登陸或者有關支付確認的界面，經常會用到驗證碼，驗證碼有的是通過手機發送獲取的，有的是在本地點擊獲取的，通過手機發送獲取的動態驗證碼可以使用第三方類庫實現，本地點擊獲取的是在本地自己繪制的，下面我們來詳細講解一下本地生成動態驗證碼的過程。

<一>導入CoreGraphics.framework

<二>驗證碼封裝了一個UIView，在使用的時候直接把這個View加到界面上使用

　　CaptchaView.h

#import  @interface CaptchaView : UIView @property (nonatomic, retain) NSArray *changeArray; //字符素材數組 @property (nonatomic, retain) NSMutableString *changeString; //驗證碼的字符串 @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; //設置layer圓角半徑 self.layer.masksToBounds = YES; //隱藏邊界 self.backgroundColor = kRandomColor; //顯示一個隨機驗證碼 [self changeCaptcha]; } return self; } #pragma mark 更換驗證碼,得到更換的驗證碼的字符串 -(void)changeCaptcha { //<一>從字符數組中隨機抽取相應數量的字符，組成驗證碼字符串 //數組中存放的是全部可選的字符，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,@傑,@瑞,@教,@育,nil]; //如果能確定最大需要的容量，使用initWithCapacity:來設置，好處是當元素個數不超過容量時，添加元素不需要重新分配內存 NSMutableString *getStr = [[NSMutableString alloc] initWithCapacity:kCharCount]; self.changeString = [[NSMutableString alloc] initWithCapacity:kCharCount]; //隨機從數組中選取需要個數的字符，然後拼接為一個字符串 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>從網絡獲取字符串，然後把得到的字符串在本地繪制出來（網絡獲取步驟在這省略） // self.changeString = [NSMutableString stringWithString:@傑瑞教育]; } #pragma mark 點擊view時調用，因為當前類自身就是UIView，點擊更換驗證碼可以直接寫到這個方法中，不用再額外添加手勢 -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { //點擊界面，切換驗證碼 [self changeCaptcha]; //setNeedsDisplay調用drawRect方法來實現view的繪制 [self setNeedsDisplay]; } #pragma mark 繪制界面（1.UIView初始化後自動調用； 2.調用setNeedsDisplay方法時會自動調用） - (void)drawRect:(CGRect)rect { // 重寫父類方法，首先要調用父類的方法 [super drawRect:rect]; //設置隨機背景顏色 self.backgroundColor = kRandomColor; //獲得要顯示驗證碼字符串，根據長度，計算每個字符顯示的大概位置 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; //依次繪制每一個字符,可以設置顯示的每個字符的字體大小、顏色、樣式等 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}]; } //調用drawRect：之前，系統會向棧中壓入一個CGContextRef，調用UIGraphicsGetCurrentContext()會取棧頂的CGContextRef CGContextRef context = UIGraphicsGetCurrentContext(); //設置畫線寬度 CGContextSetLineWidth(context, kLineWidth); //繪制干擾的彩色直線 for(int i = 0; i < kLineCount; i++) { //設置線的隨機顏色 UIColor *color = kRandomColor; CGContextSetStrokeColorWithColor(context, [color CGColor]); //設置線的起點 pX = arc4random() % (int)rect.size.width; pY = arc4random() % (int)rect.size.height; CGContextMoveToPoint(context, pX, pY); //設置線終點 pX = arc4random() % (int)rect.size.width; pY = arc4random() % (int)rect.size.height; CGContextAddLineToPoint(context, pX, pY); //畫線 CGContextStrokePath(context); } } @end

<三>在界面上添加驗證碼

　　ViewController.m

#import ViewController.h #import CaptchaView.h @interface ViewController () { CaptchaView *_captchaView; UITextField *_input; } @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; //顯示驗證碼界面 _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 = @點擊圖片換驗證碼; label.font = [UIFont systemFontOfSize:12]; label.textColor = [UIColor grayColor]; [self.view addSubview:label]; //添加輸入框 _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 = @請輸入驗證碼!; _input.clearButtonMode = UITextFieldViewModeWhileEditing; _input.backgroundColor = [UIColor clearColor]; _input.textAlignment = NSTextAlignmentCenter; _input.returnKeyType = UIReturnKeyDone; _input.delegate = self; [self.view addSubview:_input]; } #pragma mark 輸入框協議中方法,點擊return按鈕 - (BOOL)textFieldShouldReturn:(UITextField *)textField { //判斷輸入的是否為驗證圖片顯示的驗證碼 if ([_input.text isEqualToString:_captchaView.changeString]) { //正確彈出警告款提示正確 UIAlertView *alview = [[UIAlertView alloc] initWithTitle:@恭喜您 ^o^ message:@驗證成功 delegate:self cancelButtonTitle:@OK otherButtonTitles:nil, nil]; [alview show]; } else { //驗證不匹配，驗證碼和輸入框晃動 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 { //清空輸入框內容，收回鍵盤 if (buttonIndex==0) { _input.text = @; [_input resignFirstResponder]; } } @end

 

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