根据数字，转成对应的图片

- (void)viewDidLoad {
    [super viewDidLoad];

    [self testNum2String:10086];
}

/// 根据数字，显示对应的图片 数字用特定的图片显示
- (void)testNum2String:(NSInteger)num {
    
    UIView *numContentView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 0, 20)];
    numContentView.backgroundColor = UIColor.redColor;
    
    NSString *str = [NSString stringWithFormat:@"%zd", num];
    NSInteger length = str.length;
    for (int i = 0; i < length; i++) {
        // 取到每一位数字 这一行是关键代码
        char ch = [str characterAtIndex:i];
        
        NSLog(@"word is %c", ch);
        NSString *imgName = [NSString stringWithFormat:@"icon_num_%c", ch];
        // 根据数字，取对应的图片
        UIImage *img = [UIImage imageNamed:imgName];
        UIImageView *imgView = [[UIImageView alloc] initWithImage:img];
        imgView.frame = CGRectMake(numContentView.frame.size.width, 0, 10, 20);
        [numContentView addSubview:imgView];
        numContentView.frame = CGRectMake(100, 100, CGRectGetMaxX(imgView.frame), 20);
    }
    
    [self.view addSubview:numContentView];
}