iOS 绘制图片随机验证码

   <p style="text-align:center"><img src="https://simg.open-open.com/show/86441224844cc29995e3ff6e034c87e6.gif"></p>    <p style="text-align:center">2016-07-18 17_31_51.gif</p>    <h3><strong>.h文件</strong></h3>    <pre>  <code class="language-objectivec">@property (nonatomic, retain) NSArray *changeArray;  @property (nonatomic, retain) NSMutableString *changeString;  @property (nonatomic, retain) UILabel *codeLabel;    -(void)changeCode;  @end</code></pre>    <h3><strong>.m文件</strong></h3>    <pre>  <code class="language-objectivec">@synthesize changeArray = _changeArray;  @synthesize changeString = _changeString;  @synthesize codeLabel = _codeLabel;    - (id)initWithFrame:(CGRect)frame  {      self = [super initWithFrame:frame];      if (self) {          // Initialization code            float red = arc4random() % 100 / 100.0;          float green = arc4random() % 100 / 100.0;          float blue = arc4random() % 100 / 100.0;          UIColor *color = [UIColor colorWithRed:red green:green blue:blue alpha:0.2];          self.backgroundColor = color;          [self change];      }      return self;  }    -(void)changeCode  {      [self change];      [self setNeedsDisplay];  }    - (void)change  {      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",nil];        NSMutableString *getStr = [[NSMutableString alloc] initWithCapacity:5];        self.changeString = [[NSMutableString alloc] initWithCapacity:6];      for(NSInteger i = 0; i < 4; i++)      {          NSInteger index = arc4random() % ([self.changeArray count] - 1);          getStr = [self.changeArray objectAtIndex:index];            self.changeString = (NSMutableString *)[self.changeString stringByAppendingString:getStr];      }  }    - (void)drawRect:(CGRect)rect   {      [super drawRect:rect];        float red = arc4random() % 100 / 100.0;      float green = arc4random() % 100 / 100.0;      float blue = arc4random() % 100 / 100.0;        UIColor *color = [UIColor colorWithRed:red green:green blue:blue alpha:0.5];      [self setBackgroundColor:color];        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;        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:[UIFont systemFontOfSize:20]}];      }        CGContextRef context = UIGraphicsGetCurrentContext();      CGContextSetLineWidth(context, 1.0);      for(int cout = 0; cout < 10; cout++)      {          red = arc4random() % 100 / 100.0;          green = arc4random() % 100 / 100.0;          blue = arc4random() % 100 / 100.0;          color = [UIColor colorWithRed:red green:green blue:blue alpha:0.2];          CGContextSetStrokeColorWithColor(context, [color CGColor]);          pX = arc4random() % (int)rect.size.width;          pY = arc4random() % (int)rect.size.height;          CGContextMoveToPoint(context, pX, pY);          pX = arc4random() % (int)rect.size.width;          pY = arc4random() % (int)rect.size.height;          CGContextAddLineToPoint(context, pX, pY);          CGContextStrokePath(context);      }  }  @end</code></pre>    <h3><strong>VIewController中调用</strong></h3>    <pre>  <code class="language-objectivec">_codeView = [[CodeView alloc] initWithFrame:CGRectMake(15+(SCREEN_WIDTH-30)/3*2, 75, (SCREEN_WIDTH-30)/3, 39)];   //手势  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapClick:)];  [_codeView addGestureRecognizer:tap];  [self.view addSubview: _codeView];</code></pre>    <h3><strong>手势事件</strong></h3>    <pre>  <code class="language-objectivec">- (void)tapClick:(UITapGestureRecognizer*)tap  {      [_codeView changeCode];  }</code></pre>    <p> </p>    <p>来自：http://www.jianshu.com/p/b55c1251c4cd</p>    <p> </p>