在 iOS 8 中，我尝试将 UIImageView 添加为 UITextView 的子视图，类似于此处显示的内容 - 但在图像下方显示文本。
我想使用排除路径来执行此操作，因为在其他设备上，我可能会根据屏幕尺寸以不同方式定位图像。
但是有一个问题，如果用于创建排除路径的 CGRect 的 Y 原点为 0，并且占据了 textView 的整个宽度，则排除失败并且文本出现在排除路径中（因此文本显示在imageView，正如您在该屏幕截图中看到的那样）。
为了测试这一点，我使用“单一视图”Xcode 模板构建了一个简单的应用程序，其中包含以下内容：
- (void)viewDidLoad {
[super viewDidLoad];
// set up the textView
CGRect frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
UITextView *textView = [[UITextView alloc] initWithFrame:frame];
[textView setFont:[UIFont systemFontOfSize:36.0]];
[self.view addSubview:textView];
textView.text = @"I wish this text appeared below the exclusion rect and not within it.";
// add the photo
CGFloat textViewWidth = textView.frame.size.width;
// uncomment if you want to see that the exclusion path DOES work when not taking up the full width:
// textViewWidth = textViewWidth / 2.0;
CGFloat originY = 0.0;
// uncomment if you want to see that the exclusion path DOES work if the Y origin isn't 0
// originY = 54.0;
UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"photo_thumbnail"]];
imageView.frame = CGRectMake(0, originY, textViewWidth, textViewWidth);
imageView.alpha = 0.7; // just so you can see that the text is within the exclusion path (behind photo)
[textView addSubview:imageView];
// set the exclusion path (to the same rect as the imageView)
CGRect exclusionRect = [textView convertRect:imageView.bounds fromView:imageView];
UIBezierPath *exclusionPath = [UIBezierPath bezierPathWithRect:exclusionRect];
textView.textContainer.exclusionPaths = @[exclusionPath];
}
我还尝试继承 NSTextContainer 并覆盖 -lineFragmentRectForProposedRect 方法，但在那里调整 Y 原点似乎也无济于事。
为了使用自定义的 NSTextContainer，我在 viewDidLoad() 中像这样设置 UITextView 堆栈：
// set up the textView stack
NSTextStorage *textStorage = [[NSTextStorage alloc] init];
NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
[textStorage addLayoutManager:layoutManager];
CGSize containerSize = CGSizeMake(self.view.frame.size.width, CGFLOAT_MAX);
CustomTextContainer *textContainer = [[CustomTextContainer alloc] initWithSize:containerSize];
[layoutManager addTextContainer:textContainer];
CGRect frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
UITextView *textView = [[UITextView alloc] initWithFrame:frame textContainer:textContainer];
[textView setFont:[UIFont systemFontOfSize:36.0]];
[self.view addSubview:textView];
textView.text = @"I wish this text appeared below the exclusion rect and not within it.";
然后我像这样调整 CustomTextContainer 中的 Y 原点......但这同样失败了：
- (CGRect)lineFragmentRectForProposedRect:(CGRect)proposedRect atIndex:(NSUInteger)characterIndex writingDirection:(NSWritingDirection)baseWritingDirection remainingRect:(CGRect *)remainingRect {
CGRect correctedRect = proposedRect;
if (correctedRect.origin.y == 0) {
correctedRect.origin.y += 414.0;
}
correctedRect = [super lineFragmentRectForProposedRect:correctedRect atIndex:characterIndex writingDirection:baseWritingDirection remainingRect:remainingRect];
NSLog(@"origin.y: %f | characterIndex: %lu", correctedRect.origin.y, (unsigned long)characterIndex);
return correctedRect;
}
我想这可以被认为是我需要报告的 Apple 错误（除非我遗漏了一些明显的东西），但如果有人有解决方法，将不胜感激。