jixin_new/shiku_im/util/GALCaptcha.m

//
//  GALCaptcha.m
//  shiku_im
//
//  Created by JayLuo on 2020/1/14.
//  Copyright © 2020 Reese. All rights reserved.
//

#import "GALCaptcha.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  //干扰线条数
#define kLineWidth 1.0 //线宽
#define kCharCount 4   //字符个数
#define kFontSize [UIFont systemFontOfSize:arc4random() % 5 + 15]


@implementation GALCaptcha

-(instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        self.layer.cornerRadius = 5.0;
        self.layer.masksToBounds = YES;
        self.backgroundColor = [UIColor greenColor];
        
        //显示一个随机验证码
        [self showCaptcha];

    }
    
    return self;
}

- (void)refresh {
    //点击界面，切换验证码
        [self showCaptcha];
        
        //setNeedsDisplay调用drawRect方法来实现view的绘制
        [self setNeedsDisplay];
}

-(void)showCaptcha
{
    //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.CatArray = [[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",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.CatString = [[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.CatArray count] - 1);
        getStr = [self.CatArray objectAtIndex:index];
        
        self.CatString = (NSMutableString *)[self.CatString 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 showCaptcha];
    
    //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.CatString];
    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);
        
//       //设置线条起点和终点的样式为圆角
//        CGContextSetLineCap(context, kCGLineCapRound);
//       //设置线条的转角的样式为圆角
//        CGContextSetLineJoin(context, kCGLineJoinRound);
        //画线
        CGContextStrokePath(context);
    }
}

@end