IOS研究之网络编程(二)-Cocoa Streams使用具体解释

本文以及相关的系列文章是我总结的iOS网络开发方面的知识点，本文是第二篇，主要分析了Cocoa Streams中的几个重要类

Cocoa Streams实际上是Objective-C对CFNetwork的简单封装，主要包括了三个类:NSStream, NSInputStream, and NSOutputStream。本部分的接口接口比較简单，使用方法一目了然。

我在这里就仅仅列出接口，方便查阅。

对CFNnework不明确的看IOS研究之网络编程(一)-CFNetwork使用具体解释
NSStream接口例如以下:

@interface NSStream : NSObject  
- (void)open;  
- (void)close;  
  
- (id <NSStreamDelegate>)delegate;  
- (void)setDelegate:(id <NSStreamDelegate>)delegate;  
    // By default, a stream is its own delegate, and subclassers of NSInputStream and NSOutputStream must maintain this contract. [someStream setDelegate:nil] must restore this behavior. As usual, delegates are not retained.  
  
- (id)propertyForKey:(NSString *)key;  
- (BOOL)setProperty:(id)property forKey:(NSString *)key;  
  
- (void)scheduleInRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode;  
- (void)removeFromRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode;  
  
- (NSStreamStatus)streamStatus;  
- (NSError *)streamError;  
@end  
  
@protocol NSStreamDelegate <NSObject>  
@optional  
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode;  
@end  
  
#if (TARGET_OS_MAC && !(TARGET_OS_EMBEDDED || TARGET_OS_IPHONE))//不能在ios上使用  
@interface NSStream (NSSocketStreamCreationExtensions)  
+ (void)getStreamsToHost:(NSHost *)host port:(NSInteger)port inputStream:(NSInputStream **)inputStream outputStream:(NSOutputStream **)outputStream;  
@end  
#endif

@interface NSStream : NSObject

- (void)open;

- (void)close;

- (id <NSStreamDelegate>)delegate;

- (void)setDelegate:(id <NSStreamDelegate>)delegate;

// By default, a stream is its own delegate, and subclassers of NSInputStream and NSOutputStream must maintain this contract. [someStream setDelegate:nil] must restore this behavior. As usual, delegates are not retained.

- (id)propertyForKey:(NSString *)key;

- (BOOL)setProperty:(id)property forKey:(NSString *)key;

- (void)scheduleInRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode;

- (void)removeFromRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode;

- (NSStreamStatus)streamStatus;

- (NSError *)streamError;

@end

@protocol NSStreamDelegate <NSObject>

@optional

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode;

@end

#if (TARGET_OS_MAC && !(TARGET_OS_EMBEDDED || TARGET_OS_IPHONE))//不能在ios上使用

@interface NSStream (NSSocketStreamCreationExtensions)

+ (void)getStreamsToHost:(NSHost *)host port:(NSInteger)port inputStream:(NSInputStream **)inputStream outputStream:(NSOutputStream **)outputStream;

@end

#endif

NSInputStream和NSOutputStream都是继承NSStream，接口例如以下

@interface NSInputStream : NSStream  
- (NSInteger)read:(uint8_t *)buffer maxLength:(NSUInteger)len;  
- (BOOL)getBuffer:(uint8_t **)buffer length:(NSUInteger *)len;  
- (BOOL)hasBytesAvailable;  
@end  
  
@interface NSOutputStream : NSStream  
- (NSInteger)write:(const uint8_t *)buffer maxLength:(NSUInteger)len;  
- (BOOL)hasSpaceAvailable;  
@end

@interface NSInputStream : NSStream

- (NSInteger)read:(uint8_t *)buffer maxLength:(NSUInteger)len;

- (BOOL)getBuffer:(uint8_t **)buffer length:(NSUInteger *)len;

- (BOOL)hasBytesAvailable;

@end

@interface NSOutputStream : NSStream

- (NSInteger)write:(const uint8_t *)buffer maxLength:(NSUInteger)len;

- (BOOL)hasSpaceAvailable;

@end

但这里getStreamsToHost方法,在iOS上不可用。那么在iOS上改怎样初始化NSStream呢？这事实上是iOS的一个小bug。苹果已经给出了答案，须要我们自己为NSStream加入一个类目: