如何像 Facebook instagram 一样标记 imageview。在 ios 中（在 imageview 上标记坐标）

Question

我想在 imageview 上标记一些东西，并且必须存储在数据库中，当我从数据库中检索它时，我必须在 imageview 上显示相同的坐标。

Answer 1

您在情节提要（或代码）中创建 UIImageView，并在 viewController 中创建 fowling 属性：

@property (strong, nonatomic) UITapGestureRecognizer *tapGesture;

接下来，在viewDidLoad中初始化tapGesture：

self.tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTapGesture:)];

self.tapGesture.delegate = self;

[self.view addGestureRecognizer:self.tapGesture];

接下来，为点击创建处理程序：

- (void)handleSingleTapGesture:(UITapGestureRecognizer *)tapGestureRecognizer {

    CGPoint point = [tapGestureRecognizer locationInView:self.imageView];
    float squareSize = 10;

    UIGraphicsBeginImageContextWithOptions(self.imageView.frame.size, YES, 0);

    [self.imageView.image drawInRect:CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height)];

    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), point.x-squareSize, point.y - squareSize);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), point.x+squareSize, point.y-squareSize);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), point.x+squareSize, point.y+squareSize);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), point.x-squareSize, point.y+squareSize);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), point.x-squareSize, point.y-squareSize);
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 1);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0,0,0,1);
    CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);

    CGContextStrokePath(UIGraphicsGetCurrentContext());
    self.imageView.image = UIGraphicsGetImageFromCurrentImageContext();
    [self.imageView setAlpha:1.0];
    UIGraphicsEndImageContext();

}

此代码在 imageView 上绘制一个正方形。现在您可以将point 保存在您的数据库中，并在需要显示图像时绘制方形标签。

希望对你有所帮助。