iOS隨機改變背景色及顯示數字

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附上代碼，類似於註冊網站上的驗證碼

付圖：

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- (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:1.0];

    [self setBackgroundColor:color];

    

    NSString *text = [NSString stringWithFormat:@"%@",self.changeString];

    CGSize cSize = [@"S" sizeWithFont:[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++)

    {

        NSLog(@"rect.size.width / text.length * i%f",rect.size.width / 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 withFont:[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:1.0];

        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);

    }

}

iOS隨機改變背景色及顯示數字