NSNotificationCenter

- (void)addObserver:(id)observer selector:(SEL)aSelector :(NSString *)aName object:(id)anObject;

register to receive notification

parameter:

1. observer: the object to receive notification

2. aName: name of notification, if it is nil, we receive all notifications sent out by anObject

3. anObject: specify object we want to observe. If it is nil, we receive all notification with aName

we can register many objects to receive same notification.

- (void)postNotificationName:(NSString *)aName object:(id)anObject;

send notfication

parameter:

anObject: sender

responder chain in iOS & Cocoa

events are passed through responder chain

ex:
if first responder is view A
when view A does not handle event, it forward event to next responder, its view controller
if view controller  does not handle event, it forward event to view A's parent view B
if view B does not handle event, it forward event to its view controller
Hence,  sequence is
view A ->  view A's view controller -> view A's parent view B -> view A's parent view B's view controller
note:
if event is passed through all view hierarchy, it is then passed to app's window. If window does not handle event, it is passed to UIApplication object

forward an event:
ex:
[self.nextResponder processEvent:event];

operation is iOS SDK

Add operations into operation queue and queue will manage operation for us

operation type:
1. Block operation
2. Invocation operation
3. Plane operation

operation 執行的順序和加入operation queue的順序無關

gcd: Grand Central Dispatch

provide a number of predefined queues

we can create our own queue

queue is FIFO

custom delegate

兩個物件之間通訊的方式有很多，
透過自行訂義的@protocol是其中一種。
而我們往往將protocol名字取名為某種delegate。

將NSString變為合法的URL

使用

- (NSString *)stringByAddingPercentEscapesUsingEncoding:(NSStringEncoding)enc

ex:

url = [url   

      stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

Download File Asynchronously

利用NSURLConnection的initWithRequest:delegate:startImmediately: method建立connection，

於startImmediately傳入yes表示馬上開始download

NSURL *url = [NSURL URLWithString:urlStr];

self.downloadData = [[NSMutableData alloc] init];

[self.downloadData release];

NSURLRequest *req = [NSURLRequest requestWithURL:url];

self.downloadConnection = [[NSURLConnection alloc] 

                                   initWithRequest:req  

                                   delegate:self

                                   startImmediately:YES];

[self.downloadConnection release];


常用的NSURLConnectionDelegate method


開始download後，首先被呼叫的method
由於一個request可能收到多個response，
所以將data的長度設為0，
清除之前收到的data

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{

    NSLog(@"didReceiveResponse");

    [self.downloadData setLength:0];

}

將收到的data累加進downloadData

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

    NSLog(@"data %d", [data length]);

    [self.downloadData appendData:data];

}

成功完成下載時被呼叫

- (void)connectionDidFinishLoading:(NSURLConnection *)connection

{

    NSLog(@"Successfully connectionDidFinishLoading");

}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error

{

    NSLog(@"error %@", error);

}

測試輸出:

2011-03-26 17:50:00.690 DownloadAsync[13125:207] didReceiveResponse

2011-03-26 17:50:00.692 DownloadAsync[13125:207] data 3310

2011-03-26 17:50:00.693 DownloadAsync[13125:207] data 13258

2011-03-26 17:50:00.694 DownloadAsync[13125:207] Successfully connectionDidFinishLoading

Download File Synchronously

利用NSURLConnection的sendSynchronousRequest:returningResponse:error: method

NSString *urlStr = @"http://deeploveapple.blogspot.com/";

NSURL *url = [NSURL URLWithString:urlStr];

NSURLRequest *req = [NSURLRequest requestWithURL:url];

NSError *error = nil;

NSData *data = [NSURLConnection sendSynchronousRequest:req   

   returningResponse:nil error:&error];

if(data)

{

   NSString *str = [[NSString alloc] initWithData:data                                           

      encoding:NSUTF8StringEncoding];

   NSLog(@"str %@", str);

   [str release];

}

else

{

   NSLog(@"error %@", error);

}

利用NSXMLParser parse梁朝偉和劉德華

xml檔範例:

<?xml version="1.0" encoding="UTF-8"?>

    <永遠的偶像>

        <名字 name="梁朝偉">

            <音樂>為情所困</音樂>

            <movie>俠骨仁心</movie>

        </名字>

        <名字 name="劉德華">

            <音樂>來生緣</音樂>

            <movie>孤男寡女</movie>

        </名字>

    </永遠的偶像>

</xml>

利用xml檔案初始NSXMLParser物件
NSData *data = [NSData dataWithContentsOfFile:path];

xmlParser = [[NSXMLParser alloc] initWithData:data];

設定delegate，如此才能於NSXMLParserDelegate的method被呼叫時做處理

[xmlParser setDelegate:self];

 呼叫NSXMLParser物件的parse method開始進行parse
 parse method is a block call，做完才return

[xmlParser parse];

[xmlParser release];

以下三個method為我們最常使用的NSXMLParserDelegate method


1. 於遇到XML tag開頭時被呼叫，可取得tag的名稱以及tag裡的attribute

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict

{

    NSLog(@"didStartElement");

    NSLog(@"elementName %@", elementName);

    for(id key in attributeDict)

    {

        NSLog(@"attribute %@", [attributeDict objectForKey:key]);

    }

}

2. 找到XML tag所包含的內容

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

{

    NSLog(@"foundCharacters %@", string);

}

3. 於遇到XML tag結尾時被呼叫

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName

{

    NSLog(@"didEndElement");

    NSLog(@"elementName %@", elementName);    

}

測試輸出:

2011-03-26 16:04:46.172 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.175 XmlParse[12296:207] elementName 永遠的偶像

2011-03-26 16:04:46.177 XmlParse[12296:207] foundCharacters 

        

2011-03-26 16:04:46.178 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.179 XmlParse[12296:207] elementName 名字

2011-03-26 16:04:46.179 XmlParse[12296:207] attribute 梁朝偉

2011-03-26 16:04:46.180 XmlParse[12296:207] foundCharacters 

            

2011-03-26 16:04:46.181 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.181 XmlParse[12296:207] elementName 音樂

2011-03-26 16:04:46.182 XmlParse[12296:207] foundCharacters 為情所困

2011-03-26 16:04:46.183 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.184 XmlParse[12296:207] elementName 音樂

2011-03-26 16:04:46.185 XmlParse[12296:207] foundCharacters 

            

2011-03-26 16:04:46.185 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.186 XmlParse[12296:207] elementName movie

2011-03-26 16:04:46.187 XmlParse[12296:207] foundCharacters 俠骨仁心

2011-03-26 16:04:46.188 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.189 XmlParse[12296:207] elementName movie

2011-03-26 16:04:46.190 XmlParse[12296:207] foundCharacters 

        

2011-03-26 16:04:46.191 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.192 XmlParse[12296:207] elementName 名字

2011-03-26 16:04:46.193 XmlParse[12296:207] foundCharacters 

        

2011-03-26 16:04:46.194 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.195 XmlParse[12296:207] elementName 名字

2011-03-26 16:04:46.196 XmlParse[12296:207] attribute 劉德華

2011-03-26 16:04:46.196 XmlParse[12296:207] foundCharacters 

            

2011-03-26 16:04:46.197 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.198 XmlParse[12296:207] elementName 音樂

2011-03-26 16:04:46.198 XmlParse[12296:207] foundCharacters 來生緣

2011-03-26 16:04:46.199 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.200 XmlParse[12296:207] elementName 音樂

2011-03-26 16:04:46.201 XmlParse[12296:207] foundCharacters 

            

2011-03-26 16:04:46.202 XmlParse[12296:207] didStartElement

2011-03-26 16:04:46.202 XmlParse[12296:207] elementName movie

2011-03-26 16:04:46.203 XmlParse[12296:207] foundCharacters 孤男寡女

2011-03-26 16:04:46.204 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.204 XmlParse[12296:207] elementName movie

2011-03-26 16:04:46.206 XmlParse[12296:207] foundCharacters 

        

2011-03-26 16:04:46.206 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.207 XmlParse[12296:207] elementName 名字

2011-03-26 16:04:46.208 XmlParse[12296:207] foundCharacters 

    

2011-03-26 16:04:46.210 XmlParse[12296:207] didEndElement

2011-03-26 16:04:46.212 XmlParse[12296:207] elementName 永遠的偶像

NSData

+(id)dataWithContentsOfFile:(NSString *)path;

從檔案產生NSData物件

NSString & NSMutableString

-(NSString *)stringByAppendingString:(NSString *)aString;

將aString加到原來字串的結尾

NSDictionary & NSMutableDictionary

-(void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;

將otherDictionary裡的elements加入dic裡