NSLayoutManager委托未調用

Question

我想知道為什么我的委托方法

- (void)layoutManager:(NSLayoutManager *)layoutManager
didCompleteLayoutForTextContainer:(NSTextContainer *)textContainer
                atEnd:(BOOL)layoutFinishedFlag

不被稱為，我用了這段代碼：

self.storage = [[NSTextStorage alloc] initWithString:@"sdfsdf sdf sdf sdf sdf sdf Sdf sdf sdf "];
self.layout = [[NSLayoutManager alloc] init];
[self.storage addLayoutManager:self.layout];
self.layout.delegate = self;
NSTextContainer * container = [[NSTextContainer alloc] init];
[self.layout addTextContainer:container];

TextStorage和LayoutManager屬性在類中保留很強，但是未調用委托方法！！！

Answer 1

在設置委托后修改NSTextStorage時，將調用委托方法。 這是UIViewController的片段：

- (void)viewDidLoad {
    [super viewDidLoad];
    self.layout = [[NSLayoutManager alloc] init];
    self.layout.delegate = self;
    self.storage = [[NSTextStorage alloc] init];
    [self.storage addLayoutManager:self.layout];
    NSTextContainer * container = [[NSTextContainer alloc] init];
    [self.layout addTextContainer:container];
    NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"New string"];
    [self.storage setAttributedString:string];
}

- (void)layoutManager:(NSLayoutManager *)layoutManager
didCompleteLayoutForTextContainer:(NSTextContainer *)textContainer
                atEnd:(BOOL)layoutFinishedFlag
{
    NSLog(@"I'm here");
}

Answer 2

我發現將任何容器添加到UITextView時也會調用該委托方法。