如何使UIImageView适合缩放图像

UIImageView是iOS开发中用于显示图像的控件。要使UIImageView适合缩放图像，可以通过以下步骤实现：

设置UIImageView的contentMode属性为UIViewContentModeScaleAspectFit。这将确保图像在保持纵横比的同时适应UIImageView的尺寸。代码示例：

imageView.contentMode = .scaleAspectFit

如果需要允许用户手势缩放图像，可以使用UIPinchGestureRecognizer来实现缩放功能。代码示例：

let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(handlePinchGesture(_:)))
imageView.addGestureRecognizer(pinchGesture)
imageView.isUserInteractionEnabled = true

@objc func handlePinchGesture(_ gesture: UIPinchGestureRecognizer) {
    guard let view = gesture.view else { return }
    view.transform = view.transform.scaledBy(x: gesture.scale, y: gesture.scale)
    gesture.scale = 1.0
}

如果需要限制缩放的最小和最大比例，可以在手势处理方法中添加逻辑来控制缩放范围。代码示例：

@objc func handlePinchGesture(_ gesture: UIPinchGestureRecognizer) {
    guard let view = gesture.view else { return }
    
    let minScale: CGFloat = 0.5
    let maxScale: CGFloat = 2.0
    
    var currentScale = view.frame.size.width / view.bounds.size.width
    let newScale = currentScale * gesture.scale
    
    if newScale < minScale {
        currentScale = minScale
    } else if newScale > maxScale {
        currentScale = maxScale
    } else {
        currentScale = newScale
    }
    
    view.transform = CGAffineTransform(scaleX: currentScale, y: currentScale)
    gesture.scale = 1.0
}

适用场景：