UIView drawRect;类变量超出范围 [英] UIView drawRect; class variables out of scope

问题描述

短&

我有一个UIVIew与一个init和一个drawrect方法（和另一个线程和一堆其他东西，但是，

在 - （id）init方法中分配的所有类变量和init都超出范围/ nil / p>

例如：

在接口：

  NSObject * fred; 
  

在实施中：

   - （id）init 
 {
 if（self == [super init]）
 {
 fred = [[NSObject alloc] init]; 
} 
 
 return self; 
} 
 
  - （void）drawRect：（CGRect）rect 
 {
 NSLog（@Fred保留％i次，[fred retainCount]）; // FAIL 
 NSLog（@但是他的变量实际上只是指向未初始化的0x0，所以你不会在调试器中读取这个，因为应用程序在它到达之前已经崩溃了。
} 
 

应该在drawRect之前调用init IS。任何人都有什么想法？

解决方案

它实际上是调用 NSLog














编辑：一些简短的测试显示，问题不是fred未初始化;如果是;你不会收到任何错误，因为发送消息到 nil 不会导致崩溃（实例变量被初始化为 nil ）发生了什么事实， code> fred 被释放;导致指针指向垃圾，而不是一个对象（或者更确切地说，一个乱码或乱码的对象，不再能接收消息。）

您提供的代码不足以找到错误;你将不得不粘贴更多（和应用程序中使用的确切代码）。

Short & sweet version of my last question in light of new information.

I have a UIVIew with an init and a drawrect method (and another thread and a bunch of other stuff, but I'll keep it short & sweet).

All of the class variables that I alloc and init in the -(id)init method are out of scope/nil/0x0 in the drawRect method, and I am unable to access them.

For example;

In the interface:

NSObject* fred;

In the implementation:

-(id)init
{
    if(self == [super init])
    {
        fred = [[NSObject alloc] init];
    }

    return self;
}

-(void)drawRect:(CGRect)rect
{
    NSLog(@"Fred is retained %i times",[fred retainCount]); //FAIL
    NSLog(@"But his variable is actually just pointing at uninitialised 0x0, so you're not reading this in the debugger because the application has crashed before it got here."
}

Should add that init IS being called before drawRect also. Anyone have any ideas?

解决方案

IS it? Have you actually put a call to NSLog in there and checked? Because I would think it's initialized with initWithFrame: or something to that effect.

Edit: Some brief testing reveals that the issue isn't that fred is uninitialized; if it was; you'd not get any error, as sending messages to nil will not cause a crash. (Instance variables are initialized to nil). What is happening, in fact, is that somewhere along the line fred is released; causing the pointer to point to garbage, rather than an object. (Or rather, a garbled or garbaged object that can no longer receive messages.)

The code you have provided is not enough to find the error; you're going to have to paste more (and the exact code used in your application, too).

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