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I've got a fixed controller with dynamic views as its view. I want to set value for property of a certain view.

Here's code in the controller as below:

@property (nonatomic, retain) Class viewClass;

- (void)viewDidLoad {
        [super viewDidLoad];
        // Do any additional setup after loading the view.
        self.view =  _viewClass.new;
        if ([_viewClass resolveInstanceMethod:@selector(lineAdded)]) {
            [_viewClass setValue:@YES forKey:@"lineAdded"];
        }
        self.view.backgroundColor = [UIColor whiteColor];
}

In * the certain* view, I've got a property like this.

@property (nonatomic, assign) BOOL lineAdded;

It reminds me

Undeclared selector 'lineAdded'

When I run, it just skip if condition and go on.

My question is: is it impossible to set property when the class it belongs to isn't specified?

Hope somebody could help me. Thanks in advance.

4

2 回答 2

0

您可以通过让编译器看到lineAdded选择器的声明来消除警告。一个包含该属性声明的头文件，或者#import以另一种方式声明它，例如：

@protocol DummyProtocol
@property (nonatomic, unsafe_unretained) BOOL lineAdded;
@end

其次，设置属性的值不需要lineAdded选择器。它需要setLineAdded:选择器。

第三，检查是否self.view响应的正确方法setLineAdded:是询问它，如下所示：

    if ([self.view respondsToSelector:@selector(setLineAdded:)]) {
        [self.view setValue:@YES forKey:@"lineAdded"];
    }

第四，您询问_viewClass其实例是否响应lineAdded，但随后您询问_viewClass对象本身（而不是self.view它的实例）设置其自己的lineAdded属性。我在上面的代码中修复了这个问题。

第五，您应该分配给self.viewin loadView，而不是 in viewDidLoad。

毕竟，如果它不是设置lineAdded，那么您的视图（无论您选择什么类）根本不会响应setLineAdded:.

于 2015-12-19T10:23:50.970 回答
0

当您设置@YES. 您应该声明它NSNumber而不是使用原始数据类型：BOOL. 当你检索时，你应该使用-(BOOL)boolean方法来检索它。至于resolveInstanceMethod，我认为您应该查看此文档以确保您输入的逻辑正确。

https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtDynamicResolution.html

于 2015-12-19T10:22:46.040 回答