Question

在一些Apple Iphone示例中，一些属性在头文件中声明，而一些属性在实现文件中声明。例如，在Siesmic XML示例中

ParseOperation.h

@interface ParseOperation : NSOperation {
NSData *earthquakeData;

@private
NSDateFormatter *dateFormatter;

// these variables are used during parsing
Earthquake *currentEarthquakeObject;
Contact *currentContactObject;
NSMutableArray *currentParseBatch;
NSMutableString *currentParsedCharacterData;

BOOL accumulatingParsedCharacterData;
BOOL didAbortParsing;
NSUInteger parsedEarthquakesCounter;
}

@property (copy, readonly) NSData *earthquakeData;

@end

ParseOperation.m

@interface ParseOperation () <NSXMLParserDelegate>
  @property (nonatomic, retain) Earthquake *currentEarthquakeObject;
  @property (nonatomic, retain) NSMutableArray *currentParseBatch;
  @property (nonatomic, retain) NSMutableString *currentParsedCharacterData;
  @property (nonatomic, retain) Contact *currentContactObject;
@end

实现文件中附加接口声明的用途是什么？

Answer 1

这只是公共和私有类接口之间的区别。标题描述了公共接口，但是某些属性仅供类本身使用，而不是由其协作者使用。这些私有属性通常以您描述的方式声明，作为实现文件中的类别或类扩展。

// Foo.h – the public interface
@interface Foo : NSObject {…}

// Collaborators can only read bar.
@property(readonly) int bar;
@property(readonly) int baz;

@end

// Foo.m
#import "Foo.h"

// Private interface
@interface Foo ()

// Inside class implementation we can also change bar.
@property(assign) int bar;
@property(assign) int other;

@end

@implementation Foo
@synthesize bar, baz, other;
…
@end

实现文件中重复类接口声明的重点是什么？

1 个答案: