问题描述
我正在使用Xcode 4.4.1。当我定义 @property ，如 UINavigationController 或 NSArray in。 h文件我必须在.m文件中 @synthesize 。但是一些 @property 喜欢 UITabBarController 或 NSString 我不知道它必须 @synthesize 才能使它工作。
I am using Xcode 4.4.1. When I define @property like UINavigationController or NSArrayin .h file I have to @synthesize it in .m file. But some @property like UITabBarController or NSString I don't have to @synthesize it to make it work.
我的问题是什么 @ property 需要 @synthesize 以及什么不需要。
My Question is what @propertys need to @synthesize and what need not to.
AppDelegate.h
AppDelegate.h
@interface AppDelegate : UIResponder <UIApplicationDelegate>
{
UITabBarController *_tabBar;
UINavigationController *_navBar;
}
@property (strong, nonatomic) UIWindow *window;
@property (nonatomic, retain) Employee *empView;
@property (nonatomic, retain) UITabBarController *_tabBar;
@property (nonatomic, retain) UINavigationController *_navBar;
AppDelegate.m
AppDelegate.m
@implementation AppDelegate
@synthesize _navBar;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
Employee *emp = [[Employee alloc]initWithNibName:@"Employee" bundle:nil];
self._tabBar = [[UITabBarController alloc]init];
self._navBar = [[UINavigationController alloc]initWithRootViewController:emp];
self._tabBar.viewControllers = [NSArray arrayWithObjects:_navBar, nil];
self.window.rootViewController = self._tabBar;
self._navBar.navigationBar.tintColor = [UIColor brownColor];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
return YES;
}
当我 @synthesize 的UINavigationController 我得到的UINavigationController 和的UITabBarController 。但是，当我不 @合成 的UINavigationController 我不明白的UINavigationController 但显示 UITabBarController 。
When I @synthesize UINavigationController I get UINavigationController and UITabBarController. But when I don't @synthesize UINavigationController I don't get UINavigationController but UITabBarController is displayed.
在这两种情况下我都没有 @synthesize UITabBarController
In both cases I didn't @synthesize UITabBarController
谢谢
推荐答案
自上一版本的编译器（ LLVM 4.4附带的LLVM），不再需要 @synthesize 指令。
Since the last version of the compiler (LLVM) shipped with Xcode 4.4, the @synthesize directive is not needed anymore.
每 @property 你声明你不使用 @synthesize 显式地自动合成其访问器，就好像你写了 @synthesize yourprop = _yourprop; 。这是最新编译器的一个新功能（就像你必须为所有 @properties @synthesize （或实现访问器）之前一样c $ c>明确地表示。
Every @property you declare for which you don't use @synthesizeexplicitly will have its accessor synthesized automatically as if you wrote @synthesize yourprop = _yourprop;. That's a new feature of the latest compiler (as before you had to write @synthesize (or implement the accessors) for all your @properties explicitly).
注意，当然你仍然可以使用 @synthesize 属性明确的，如果你愿意（就像过去一样）。这可以是显式设计用于属性的后备实例变量的方法。但事实上我强烈建议忘记实例变量（实际上我的年龄我不会在我的 @interface的大括号之间使用显式实例变量声明了，只能使用 @property 声明。有了这个以及让编译器为你生成 @synthesize 指令的新功能，你将避免使用大量的粘合代码并使你的类更紧凑。
Note that of course you can still use the @synthesize property explicitly if you prefer to (just like old times). This can be a way to explicitly design the backing instance variable to use for the property. But as a matter of fact I strongly recommend to forget about instance variables (in fact that's ages I don't use explicit instance variables between the curly braces of my @interface declaration anymore), and only work with @property declarations. With that and the new feature that let the compiler generate the @synthesize directives for you, you will avoid a lot of glue code and make your classes more compact to write.
当你有切换警告 > @property 是隐式合成的（意思是你没有明确写出 @synthesize 指令，因此编译器现在合成它为你）。只需转到项目的Build Settings并打开Implicit Synthesized Properties警告（在Apple LLVM编译器4.0 - 警告 - Objective-C部分下），编译器将告诉您隐式的所有属性合成访问器，因为你自己没有提到 @synthesize 指令。
FYI you can toggle a warning when you have a @property for which is implicitly synthesized (meaning for which you didn't write the @synthesize directive explicitly thus for which the compiler now synthesize it for you). Simply go to the Build Settings of your project and turn on the "Implicit Synthesized Properties" warning (under "Apple LLVM compiler 4.0 - Warnings - Objective-C" section), and the compiler will tell you about all the properties for which it implicitly synthesize the accessors as you didn't mention the @synthesize directive yourself.
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