QuartzCore 的 CALayer 问题

Posted 2023-02-23

【中文标题】QuartzCore 的 CALayer 问题

【英文标题】：CALayer issues with QuartzCore

【发布时间】：2013-02-15 20:47:45

【问题描述】：

我正在使用 CAGradientLayer 来设置我的 uibuttons 样式。基本上在一个单元格中有三个按钮。当我首先设置 CAGradientLayer 属性时，它工作正常（我得到一个渐变）。

但是，当我将 CAGradientLayer 应用于第二个时，它确实出现在第二个上，但从第一个上消失了。如果我在第三个上做，那么它会在第三个出现并从前两个消失。

我应该在 UIButton 设置之间释放 CAGradientLayer 吗？

这里有一些示例代码：

 //like button
 self.likeButton=[[UIButton alloc] initWithFrame:CGRectMake(10, 430, 80, 26)];
 [self.likeButton.titleLabel setFont:[UIFont boldSystemFontOfSize:12]];
 [self.likeButton.titleLabel setTextAlignment:NSTextAlignmentLeft];
 self.likeButton.tag=indexPath.row;
 [self.likeButton addTarget:self action:@selector(likeButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
 [self.likeButton setBackgroundColor:[UIColor blackColor]];
 [self.likeButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
 [self.likeButton setTitleColor:[UIColor greenColor] forState:UIControlStateHighlighted];


 CAGradientLayer *btnGradient=[CAGradientLayer layer];
 btnGradient.frame=self.likeButton.bounds;
 btnGradient.colors=[NSArray arrayWithObjects:(id)[[UIColor colorWithRed:102.0f / 255.0f green:102.0f / 255.0f blue:102.0f / 255.0f alpha:1.0f] CGColor], (id)[[UIColor colorWithRed:41.0f / 255.0f green:41.0f / 255.0f blue:41.0f / 255.0f alpha:1.0f]CGColor], nil];
 [self.likeButton.layer insertSublayer:btnGradient atIndex:0];

 CALayer *btnLayer=self.likeButton.layer;
 [btnLayer setMasksToBounds:YES];
 [btnLayer setCornerRadius:5.0f];
 [btnLayer setBorderWidth:1.0f];
 [btnLayer setBorderColor:[[UIColor darkGrayColor]CGColor]];

 [cell addSubview:self.likeButton];


 //comment button
 UIButton *commentButton=[[UIButton alloc]initWithFrame:CGRectMake(110, 430, 80, 26)];
 [commentButton.titleLabel setFont:[UIFont boldSystemFontOfSize:12]];
 [commentButton.titleLabel setTextAlignment:NSTextAlignmentLeft];
 [commentButton setBackgroundColor:[UIColor blackColor]];
 [commentButton setTitle:@"Comment" forState:UIControlStateNormal];
 [commentButton addTarget:self action:@selector(commentButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
 [commentButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
 [commentButton setTitleColor:[UIColor greenColor] forState:UIControlStateHighlighted];


 CAGradientLayer *commentBGLayer=[CAGradientLayer layer];
 commentBGLayer.frame=commentButton.bounds;
 commentBGLayer.colors=[NSArray arrayWithObjects:(id)[[UIColor colorWithRed:102.0f / 255.0f green:102.0f / 255.0f blue:102.0f / 255.0f alpha:1.0f] CGColor], (id)[[UIColor colorWithRed:41.0f / 255.0f green:41.0f / 255.0f blue:41.0f / 255.0f alpha:1.0f]CGColor], nil];
 [commentButton.layer insertSublayer:btnGradient atIndex:0];


 CALayer *commentBLayer=commentButton.layer;
 [commentBLayer setMasksToBounds:YES];
 [commentBLayer setCornerRadius:5.0f];
 [commentBLayer setBorderWidth:1.0f];
 [commentBLayer setBorderColor:[[UIColor darkGrayColor]CGColor]];
 [cell addSubview:commentButton];

【参考方案1】：

您遇到了复制粘贴错误。您正在创建两个不同的渐变层，但您为每个按钮添加了相同的渐变层 - 这一行：

[commentButton.layer insertSublayer:btnGradient atIndex:0];

应阅读：

[commentButton.layer insertSublayer:commentBGLayer atIndex:0];