Question

CGRect rect = biggerImageView.bounds;
if([biggerImageView.layer respondsToSelector:@selector(setShadowColor:)])
{
    float shadowOffset = rect.size.width * 0.02;
    biggerImageView.layer.shadowColor = [UIColor colorWithWhite: 0.25 alpha: 0.55].CGColor;
    biggerImageView.layer.shadowOffset = CGSizeMake(shadowOffset, shadowOffset);
    biggerImageView.layer.shadowOpacity = 0.8;
    //      biggerImageView.layer.shadowPath = [UIBezierPath bezierPathWithRect: rect].CGPath;                                                                                                                                                                            
}

注释掉的线会导致阴影变得比预期的大（顶部和底部垂直较长的阴影）
我查了一下CALayer参考文献，但没有得到任何线索。

Answer 1

这可能是因为UIView bounds还不是真正的那个。（例如awakeFromNib或viewDidLoad）

等待调用视图layoutSubviews或viewController viewWillLayoutSubviews，并在那里更新影子的路径。

我创建了这个swift扩展，在我需要的任何地方添加相同的阴影（cornerRadius支持）：

import UIKit

extension UIView {
    /// Call this from `layoutSubviews` or `viewWillLayoutSubviews`.
    /// The shadow will be the same color as this view background.
    func layoutShadow() {

        // Update frame
        if let shadowView = superview?.viewWithTag(978654123) {
            shadowView.frame = frame
            shadowView.layer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: layer.cornerRadius).cgPath
            return
        }

        // Create the shadow the first time
        let shadowView = UIView(frame: frame)
        shadowView.tag = 978654123
        shadowView.translatesAutoresizingMaskIntoConstraints = false
        superview?.insertSubview(shadowView, belowSubview: self)

        shadowView.layer.shadowColor = (backgroundColor ?? UIColor.black).cgColor
        shadowView.layer.shadowOpacity = 0.8
        shadowView.layer.shadowOffset = CGSize(width: -2.0, height: 4.0)
        shadowView.layer.shadowRadius = 4.0
        shadowView.layer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: layer.cornerRadius).cgPath
    }
}

设置shadowPath时，UIImageView的阴影比预期的要大

1 个答案: