我在一个应用程序上工作了几年，收到了一个简单的设计请求:在UIView上圆角并添加投影。做以下所给的事
我想要一个自定义的UIView…:我只是想要一个空白的白色视图与圆角和光滴阴影(没有照明效果)。我可以逐个执行这些操作，但通常会发生clipToBounds/maskToBounds冲突。
当前回答
在研究了一整天的圆角视图与阴影之后，我很高兴在这里发布我的自定义uiview类，希望结束这个问题:
RoundCornerShadowView.h
#import <UIKit/UIKit.h>
@interface RoundCornerShadowView : UIView
@end
RoundCornerShadowView.m
#import "RoundCornerShadowView.h"
@implementation RoundCornerShadowView
// *** must override this method, not the other method ***
// otherwise, the background corner doesn't disappear....
// @2015/05/29
-(void) layoutSubviews {
[super layoutSubviews];//is must to ensure rightly layout children view
//1. first, create Inner layer with content
CALayer *innerView = [CALayer layer];
innerView.frame = CGRectMake(0,0,self.bounds.size.width,self.bounds.size.height);
//instead of: innerView.frame = self.frame;
innerView.borderWidth = 1.0f;
innerView.cornerRadius = 6.0f;
innerView.masksToBounds = YES;
innerView.borderColor = [[UIColor lightGrayColor] CGColor];
innerView.backgroundColor = [[UIColor whiteColor] CGColor];
//put the layer to the BOTTOM of layers is also a MUST step...
//otherwise this layer will overlay the sub uiviews in current uiview...
[self.layer insertSublayer:innerView atIndex:0];
//2. then, create shadow with self layer
self.layer.masksToBounds = NO;
self.layer.shadowColor = [[UIColor darkGrayColor] CGColor];
self.layer.shadowOpacity = 0.4f;
//shadow length
self.layer.shadowRadius = 2.0f;
//no offset
self.layer.shadowOffset = CGSizeMake(0, 0);
//right down shadow
//[self.layer setShadowOffset: CGSizeMake(1.0f, 1.0f)];
//3. last but important, MUST clear current view background color, or the color will show in the corner!
self.backgroundColor = [UIColor clearColor];
}
@end
所以，不需要在视图中添加子视图或在目标视图中添加子视图，只需在当前视图中添加一层，并执行3步即可完成!
仔细查看代码中的注释，这有助于理解组件!
其他回答
你需要使用shadowView和roundView
shadowView
必须有背景色 应该躺在roundView后面吗 窍门是将shadowView布局在里面，它的阴影需要发光。调整嵌入，使shadowView在roundView后面完全不可见
圆视图
必须剪辑子视图
的代码
addSubviews(shadowView, roundView)
roundView.addSubviews(titleLabel, subtitleLabel, imageView)
// need inset
shadowView.pinEdges(view: self, inset: UIEdgeInsets(constraintInsets: 2))
roundView.pinEdges(view: self)
do {
shadowView.backgroundColor = .white // need background
let layer = shadowView.layer
layer.shadowColor = UIColor.black.cgColor
layer.shadowRadius = 3
layer.shadowOffset = CGSize(width: 3, height: 3)
layer.shadowOpacity = 0.7
layer.shouldRasterize = true
}
do {
roundView.backgroundColor = .white
let layer = roundView.layer
layer.masksToBounds = true
layer.cornerRadius = 5
}
或者你可以在不指定clipToBounds/maskToBounds的情况下这样做
layer.shadowColor = UIColor.gray.cgColor
layer.shadowOffset = CGSize(width: 3, height: 3)
layer.shadowOpacity = 0.8
如果你因为圆角、子视图和masksToBounds而挣扎，那么尝试使用我的函数:
- (UIView*)putView:(UIView*)view insideShadowWithColor:(UIColor*)color andRadius:(CGFloat)shadowRadius andOffset:(CGSize)shadowOffset andOpacity:(CGFloat)shadowOpacity
{
CGRect shadowFrame; // Modify this if needed
shadowFrame.size.width = 0.f;
shadowFrame.size.height = 0.f;
shadowFrame.origin.x = 0.f;
shadowFrame.origin.y = 0.f;
UIView * shadow = [[UIView alloc] initWithFrame:shadowFrame];
shadow.userInteractionEnabled = NO; // Modify this if needed
shadow.layer.shadowColor = color.CGColor;
shadow.layer.shadowOffset = shadowOffset;
shadow.layer.shadowRadius = shadowRadius;
shadow.layer.masksToBounds = NO;
shadow.clipsToBounds = NO;
shadow.layer.shadowOpacity = shadowOpacity;
[view.superview insertSubview:shadow belowSubview:view];
[shadow addSubview:view];
return shadow;
}
在你的视图中调用它。无论你的视图是否有圆角，无论它的大小，它的形状-一个漂亮的阴影将被绘制出来。
只要保留函数的返回值，这样当你想要删除表时就可以引用它(或者例如使用insertSubview:aboveView:)
如果你不想像David c建议的那样改变你的nibs和视图层次结构，这个方法可以帮你。为你的UIImageView添加圆角和阴影只需使用这个方法，例如:
[Utils roundCornersForImageView:myImageView withCornerRadius:6.0
andShadowOffset:2.0];
(!)出于性能原因，我不认为在像UITableView这样的东西中使用这段代码是个好主意，因为这段代码改变了视图层次结构。所以我会建议改变你的nib，并添加一个容器视图的阴影效果和使用戴维C.代码。
+ (void)roundCornersForImageView:(UIImageView *)imageView
withCornerRadius:(float)cornerRadius andShadowOffset:(float)shadowOffset
{
const float CORNER_RADIUS = cornerRadius;
const float BORDER_WIDTH = 1.0;
const float SHADOW_OFFSET = shadowOffset;
const float SHADOW_OPACITY = 0.8;
const float SHADOW_RADIUS = 3.0;
//Our old image now is just background image view with shadow
UIImageView *backgroundImageView = imageView;
UIView *superView = backgroundImageView.superview;
//Make wider actual visible rect taking into account shadow
//offset
CGRect oldBackgroundFrame = backgroundImageView.frame;
CGRect newBackgroundFrame = CGRectMake(oldBackgroundFrame.origin.x, oldBackgroundFrame.origin.y, oldBackgroundFrame.size.width + SHADOW_OFFSET, oldBackgroundFrame.size.height + SHADOW_OFFSET);
[backgroundImageView removeFromSuperview];
backgroundImageView.frame = newBackgroundFrame;
//Make new UIImageView with rounded corners and put our old image
CGRect frameForRoundedImageView = CGRectMake(0, 0, oldBackgroundFrame.size.width, oldBackgroundFrame.size.height);
UIImageView *roundedImageView = [[UIImageView alloc]initWithFrame:frameForRoundedImageView];
roundedImageView.image = imageView.image;
[roundedImageView.layer setCornerRadius:CORNER_RADIUS];
[roundedImageView.layer setBorderColor:[UIColor lightGrayColor].CGColor];
[roundedImageView.layer setBorderWidth:BORDER_WIDTH];
[roundedImageView.layer setMasksToBounds:YES];
//Set shadow preferences
[backgroundImageView setImage:nil];
[backgroundImageView.layer setShadowColor:[UIColor blackColor].CGColor];
[backgroundImageView.layer setShadowOpacity:SHADOW_OPACITY];
[backgroundImageView.layer setShadowRadius:SHADOW_RADIUS];
[backgroundImageView.layer setShadowOffset:CGSizeMake(SHADOW_OFFSET, SHADOW_OFFSET)];
//Add out two image views back to the view hierarchy.
[backgroundImageView addSubview:roundedImageView];
[superView addSubview:backgroundImageView];
}
我尝试了这篇文章中的很多解决方案，最终得到了下面的解决方案。这是完全证明解决方案，除非你需要在一个清晰的颜色视图下滴阴影。
- (void)addShadowWithRadius:(CGFloat)shadowRadius withOpacity:(CGFloat)shadowOpacity withOffset:(CGSize)shadowOffset withColor:(UIColor *)shadowColor withCornerradius:(CGFloat)cornerRadius
{
UIView *viewShadow = [[UIView alloc]initWithFrame:self.frame];
viewShadow.backgroundColor = [UIColor whiteColor];
viewShadow.layer.shadowColor = shadowColor.CGColor;
viewShadow.layer.shadowOffset = shadowOffset;
viewShadow.layer.shadowRadius = shadowRadius;
viewShadow.layer.shadowOpacity = shadowOpacity;
viewShadow.layer.cornerRadius = cornerRadius;
viewShadow.layer.masksToBounds = NO;
[self.superview insertSubview:viewShadow belowSubview:self];
[viewShadow setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0]];
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0]];
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:viewShadow attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0]];
[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:viewShadow attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0]];
[self layoutIfNeeded];
self.layer.cornerRadius = cornerRadius;
self.layer.masksToBounds = YES;
}
下面的方法最适合我 (这段代码位于UIView扩展中，因此self表示一些我们必须添加阴影和圆角的UIView)
- (void)addShadowViewWithCornerRadius:(CGFloat)radius {
UIView *container = self.superview;
if (!container) {
return;
}
UIView *shadowView = [[UIView alloc] init];
shadowView.translatesAutoresizingMaskIntoConstraints = NO;
shadowView.backgroundColor = [UIColor lightGrayColor];
shadowView.layer.cornerRadius = radius;
shadowView.layer.masksToBounds = YES;
[container addSubview:shadowView];
[container bringSubviewToFront:shadowView];
[container addConstraint:[NSLayoutConstraint constraintWithItem:shadowView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0.0]];
[container addConstraint:[NSLayoutConstraint constraintWithItem:shadowView
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:2.0]];
[container addConstraint:[NSLayoutConstraint constraintWithItem:shadowView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:0.0]];
[container addConstraint:[NSLayoutConstraint constraintWithItem:shadowView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:2.0]];
[container sendSubviewToBack:shadowView];
}
此代码与其他代码示例之间的主要区别在于，它将阴影视图添加为兄弟视图(而不是将当前视图添加为阴影视图的子视图)，从而消除了以任何方式修改现有视图层次结构的需要。
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