xcode 在同一文件中调用返回类型为“void”的方法
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Calling a method with return type "void" in same file
提问by rottendevice
I've got a simple question.
我有一个简单的问题。
In Objective-C, when you have a method you want to call, with a return type of void, how you you call it from another method?
在 Objective-C 中，当你有一个方法要调用，返回类型为void，你如何从另一个方法调用它？
The way I've been doing it in my application is this:
我在我的应用程序中这样做的方式是这样的：
[self nameOfMethod];
But that causes Xcode to spit out the following error:
但这会导致 Xcode 吐出以下错误：
Method '-nameOfMethod' not found (return type defaults to 'id')
Though it seems to still be executing.
虽然它似乎仍在执行。
Am I calling it right, or is there a better way?
我说得对，还是有更好的方法？
Thanks!
谢谢！
回答by
I'm guessing you haven't declared -nameOfMethodin the class interface and you're calling it from another method whose implementation precedes the implementation of -nameOfMethod, i.e.:
我猜你还没有-nameOfMethod在类接口中声明，而是从另一个方法调用它，该方法的实现先于 的实现-nameOfMethod，即：
- (void)someMethod {
[self nameOfMethod];
}
- (void)nameOfMethod {
// …
}
When the compiler is parsing -someMethodand -nameOfMethodhasn't been declared in the class interface, it generates a warning because it doesn't know about -nameOfMethodyet.
当编译器正在解析-someMethod并且-nameOfMethod还没有在类接口中声明时，它会生成一个警告，因为它还不知道-nameOfMethod。
There are essentially two solutions for this. You could reorder the implementation file so that -nameOfMethodappears before -someMethod, but that's not always possible. A better solution is to declare -nameOfMethodin the class interface. If -nameOfMethodis supposed to be called by clients of your class, place it in the corresponding header file. On the other hand, if -nameOfMethodis only supposed to be called inside your implementation file, use a class extension. Supposing your class is named SomeClass, this is what your header and implementation files would look like:
对此，基本上有两种解决方案。您可以重新排序实现文件，使其-nameOfMethod出现在 之前-someMethod，但这并不总是可行的。更好的解决方案是-nameOfMethod在类接口中声明。如果-nameOfMethod应该由您的类的客户端调用，请将其放在相应的头文件中。另一方面，如果-nameOfMethod只应该在您的实现文件中调用，请使用类扩展。假设您的类名为SomeClass，这就是您的头文件和实现文件的样子：
// SomeClass.h
@interface SomeClass : NSObject {
// … instance variables
}
// … external methods
- (void)someMethod;
@end
// SomeClass.m
#import "SomeClass.h"
@interface SomeClass () // this is a class extension
// … internal methods
- (void)nameOfMethod;
@end
@implementation SomeClass
- (void)someMethod {
[self nameOfMethod];
}
- (void)nameOfMethod {
// …
}
@end
Using class extensions, the order of method implementations won't matter.
使用类扩展，方法实现的顺序无关紧要。
回答by Roger
You need to make sure that your interface file contains a definition for nameOfMethod - so;
您需要确保您的接口文件包含 nameOfMethod 的定义 - 所以；
-(void) nameOfMethod;
回答by Michael Fredrickson
You're calling it correctly, but make sure that the interface for your (void) method is in your .h file.
您正确调用了它，但请确保您的 (void) 方法的接口在您的 .h 文件中。
