我知道HIG(这非常方便!),但是在编写Objective-C时,更具体地说,在使用Cocoa(或CocoaTouch)时,您使用了什么编程实践?
当前回答
还有一个半相关的话题(还有更多的回复空间!):
有哪些Xcode的小技巧和技巧是你希望2年前就知道的?
其他回答
不要把Objective-C写成Java/ c# / c++等。
我曾经看到一个编写Java EE web应用程序的团队尝试编写Cocoa桌面应用程序。就好像它是一个Java EE web应用程序。有很多AbstractFooFactory、FooFactory、IFoo和Foo,而他们真正需要的只是一个Foo类,可能还有一个Fooable协议。
确保你不这样做的部分原因是真正理解语言的差异。例如,您不需要上面的抽象工厂和工厂类,因为Objective-C类方法和实例方法一样是动态分派的,并且可以在子类中重写。
使用LLVM/Clang静态分析仪
注意:在Xcode 4中,这是内置在IDE中。
你可以使用Clang Static Analyzer在Mac OS X 10.5上分析你的C和Objective-C代码(还没有c++)。安装和使用起来很简单:
从本页下载最新版本。 从命令行,cd到您的项目目录。 执行scan-build -k -V xcodebuild。
(还有一些额外的限制等等,特别是你应该在“调试”配置中分析一个项目——详情请参阅http://clang.llvm.org/StaticAnalysisUsage.html——但这或多或少就是它的总结。)
分析器然后为您生成一组网页,显示可能的内存管理和编译器无法检测的其他基本问题。
在dealloc中清理。
这是最容易忘记的事情之一——尤其是在以150英里/小时的速度编码时。总是,总是,总是清理dealloc中的属性/成员变量。
我喜欢使用Objc 2属性-新的点表示法-所以这使得清理变得无痛。通常很简单:
- (void)dealloc
{
self.someAttribute = NULL;
[super dealloc];
}
这将为您处理发布,并将属性设置为NULL(我认为这是防御性编程——以防dealloc中的另一个方法再次访问成员变量——很少,但也可能发生)。
在10.5中打开GC后,就不再需要这么多了——但是你可能仍然需要清理你创建的其他资源,你可以在finalize方法中做这件事。
IBOutlets
从历史上看,outlet的内存管理一直很差。 当前的最佳实践是将outlet声明为属性:
@interface MyClass :NSObject {
NSTextField *textField;
}
@property (nonatomic, retain) IBOutlet NSTextField *textField;
@end
使用属性使内存管理语义清晰;如果使用实例变量综合,它还提供了一致的模式。
其中一些已经被提到过,但以下是我能想到的:
Follow KVO naming rules. Even if you don't use KVO now, in my experience often times it's still beneficial in the future. And if you are using KVO or bindings, you need to know things are going work the way they are supposed to. This covers not just accessor methods and instance variables, but to-many relationships, validation, auto-notifying dependent keys, and so on. Put private methods in a category. Not just the interface, but the implementation as well. It's good to have some distance conceptually between private and non-private methods. I include everything in my .m file. Put background thread methods in a category. Same as above. I've found it's good to keep a clear conceptual barrier when you're thinking about what's on the main thread and what's not. Use #pragma mark [section]. Usually I group by my own methods, each subclass's overrides, and any information or formal protocols. This makes it a lot easier to jump to exactly what I'm looking for. On the same topic, group similar methods (like a table view's delegate methods) together, don't just stick them anywhere. Prefix private methods & ivars with _. I like the way it looks, and I'm less likely to use an ivar when I mean a property by accident. Don't use mutator methods / properties in init & dealloc. I've never had anything bad happen because of it, but I can see the logic if you change the method to do something that depends on the state of your object. Put IBOutlets in properties. I actually just read this one here, but I'm going to start doing it. Regardless of any memory benefits, it seems better stylistically (at least to me). Avoid writing code you don't absolutely need. This really covers a lot of things, like making ivars when a #define will do, or caching an array instead of sorting it each time the data is needed. There's a lot I could say about this, but the bottom line is don't write code until you need it, or the profiler tells you to. It makes things a lot easier to maintain in the long run. Finish what you start. Having a lot of half-finished, buggy code is the fastest way to kill a project dead. If you need a stub method that's fine, just indicate it by putting NSLog( @"stub" ) inside, or however you want to keep track of things.
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