Question

因此,在指导方针中,它说:

对于仅对iOS运行的代码,最好使用自动合成实例变量。

当合成实例变量时, 请使用 @ synthesize var = var_; 因为这样可以防止不小心调用 var = sabel; 当 self. var = label; 时使用。

 // Header file
@interface Foo : NSObject
// A guy walks into a bar.
@property(nonatomic, copy) NSString *bar;
@end

// Implementation file
@interface Foo ()
@property(nonatomic, retain) NSArray *baz;
@end

@implementation Foo
@synthesize bar = bar_;
@synthesize baz = baz_;
@end

问题是,这是否也只适用于公共变量或私人变量?这在文件上并不十分清楚,但希望对为什么“如果”只用于公共或私人?我认为,它只是所有公共/私人变量都有意义,这样你就不会搞乱伊瓦尔并使用财产。

Answer 1

我不认为这特别关系到所涉变量是公共的还是私人的。以不同名称合成的做法在直接访问变量而不是使用生成的存取器方法时就明确了。

或许在您询问的问题背后有一个不同的问题 : “ 我一般应该通过存取器还是直接访问私人的静脉? ” 我认为,最熟练的iOS deds 倾向于使用存取器,除非有某些特别的原因(表现、避免KVO等副作用 ) 。这样做更适合未来,并允许在基本执行中保持灵活性。以非常小的方式,您重新编码为接口而不是执行。

也值得指出的是,Clang的默认行为将在未来发生变化,从而将支持属性的ivars合成为默认。显然,权力(即考虑强调ivars是一种最佳做法) 。

Answer 2

我敢肯定,其中很多归结于个人偏好, 因此,这是我的, 因为它们的价值:

I like to distinguish between public properties and "private" instance vars.
Properties are always accessed through their accessors, except for initialization (and within a manually created accessor method, for obvious reasons). Hence, the underscore in the backing ivar is useful, and not really an issue in my daily use of the properties.
Instance vars are used to hold state that is used internally in the methods, but not (directly) by other classes.
I have become very fond of declaring my instance variables in the .m file. Nice, clean and easy (no switching back and forth between .h and .m to declare ivars).
I find that this distinction helps me clear my mind and determine if a property is something outside agents should get and/or set directly (a property in .h), or if it is really just a help to get my method implementations to work (an ivar in .m).

我同意保罗的观点一致性是你的朋友但对我来说区别也是朋友

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