本地验证码生成并验证-iOS

.h文件

#import 
@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

.m文件

#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 3
#define kLineWidth 1.0
#define kCharCount 5
#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 = [UIColor whiteColor];
    
    //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
{
///<>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",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];
}

}

#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 = [UIColor whiteColor];

//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

使用

 CaptchaView *  captchaView = [CaptchaView new];

if (![testStr isEqualToString:captchaView.changeString])
{
    //判断输入的是否为验证图片显示的验证码
     NSLog(@"验证码不正确");
}