【iOS】使用UIView绘制本地验证码

记录一笔：

绘制本地验证码View的一个Demo源码：（出处：http://www.cnblogs.com/jerehedu/p/4527707.html）

.h文件的代码：

1 #import <UIKit/UIKit.h>
2
3 @interface AuthCodeView : UIView
4
5 @property (nonatomic, retain) NSMutableString *changeString;  //验证码的字符串
6 @end

.m文件的代码：

  1 #import "AuthCodeView.h"
  2
  3 #define kRandomColor  [UIColor colorWithRed:arc4random() % 256 / 255.0 green:arc4random() % 256 / 255.0 blue:arc4random() % 256 / 255.0 alpha:1.0];
  4 #define kLineCount 6
  5 #define kLineWidth 1.0
  6 #define kCharCount 4
  7 #define kFontSize [UIFont systemFontOfSize:arc4random() % 5 + 18]
  8
  9 @implementation AuthCodeView
 10 @synthesize changeString;
 11
 12 - (instancetype)initWithFrame:(CGRect)frame
 13 {
 14     if (self = [super initWithFrame:frame]) {
 15
 16         self.layer.cornerRadius = 5.0; //设置layer圆角半径
 17         self.layer.masksToBounds = YES; //隐藏边界
 18         self.backgroundColor = kRandomColor;
 19
 20         //显示一个随机验证码
 21         [self refreshCode];
 22     }
 23
 24     return self;
 25 }
 26 #pragma mark 更换验证码,得到更换的验证码的字符串
 27 -(void)refreshCode {
 28     //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
 29     NSArray *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];
 30
 31     //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
 32     NSMutableString *getStr = [[NSMutableString alloc] initWithCapacity:kCharCount];
 33     self.changeString = [[NSMutableString alloc] initWithCapacity:kCharCount];
 34
 35     //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
 36     for(int i = 0; i < kCharCount; i++)
 37     {
 38         NSInteger index = arc4random() % ([changeArray count] - 1);
 39         getStr = [changeArray objectAtIndex:index];
 40
 41         self.changeString = (NSMutableString *)[self.changeString stringByAppendingString:getStr];
 42     }
 43 }
 44
 45 #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
 46 -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 47 {
 48     //点击界面，切换验证码
 49     [self refreshCode];
 50
 51     //setNeedsDisplay调用drawRect方法来实现view的绘制
 52     [self setNeedsDisplay];
 53 }
 54
 55 #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）
 56 - (void)drawRect:(CGRect)rect {
 57     // 重写父类方法，首先要调用父类的方法
 58     [super drawRect:rect];
 59
 60     //设置随机背景颜色
 61     self.backgroundColor = kRandomColor;
 62
 63     //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
 64     NSString *text = [NSString stringWithFormat:@"%@",self.changeString];
 65     CGSize cSize = [@"S" sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:20]}];
 66     int width = rect.size.width / text.length - cSize.width;
 67     int height = rect.size.height - cSize.height;
 68     CGPoint point;
 69
 70     //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
 71     float pX, pY;
 72     for (int i = 0; i < text.length; i++)
 73     {
 74         pX = arc4random() % width + rect.size.width / text.length * i;
 75         pY = arc4random() % height;
 76         point = CGPointMake(pX, pY);
 77         unichar c = [text characterAtIndex:i];
 78         NSString *textC = [NSString stringWithFormat:@"%C", c];
 79
 80         [textC drawAtPoint:point withAttributes:@{NSFontAttributeName:kFontSize}];
 81     }
 82
 83     //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
 84     CGContextRef context = UIGraphicsGetCurrentContext();
 85     //设置画线宽度
 86     CGContextSetLineWidth(context, kLineWidth);
 87
 88     //绘制干扰的彩色直线
 89     for(int i = 0; i < kLineCount; i++)
 90     {
 91         //设置线的随机颜色
 92         UIColor *color = kRandomColor;
 93         CGContextSetStrokeColorWithColor(context, [color CGColor]);
 94         //设置线的起点
 95         pX = arc4random() % (int)rect.size.width;
 96         pY = arc4random() % (int)rect.size.height;
 97         CGContextMoveToPoint(context, pX, pY);
 98         //设置线终点
 99         pX = arc4random() % (int)rect.size.width;
100         pY = arc4random() % (int)rect.size.height;
101         CGContextAddLineToPoint(context, pX, pY);
102         //画线
103         CGContextStrokePath(context);
104     }
105 }
106
107 @end

如何使用：

1 //显示验证码界面
2 AuthCodeView *codeView = [[AuthCodeView alloc] initWithFrame:CGRectMake(20, 40, 150, 40)];
3 [self.view addSubview:codeView];