IOS研究之网络编程(二)-Cocoa Streams使用详解



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，主要包含了三个类:NSStream, NSInputStream, and NSOutputStream。本部分的接口接口比较简单，用法一目了然。我在这里就只列出接口，方便查阅。对CFNnework不明白的看IOS研究之网络编程(一)-CFNetwork使用详解

NSStream接口如下:

@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

NSInputStream和NSOutputStream都是继承NSStream，接口如下

@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

但这里getStreamsToHost方法,在iOS上不可用，那么在iOS上改如何初始化NSStream呢？这其实是iOS的一个小bug，苹果已经给出了答案，需要我们自己为NSStream添加一个类目: