傳遞變量的問題 - Objective-C

Question

我想創建一個XML字符串並將其傳遞給另一個方法，我使用HTTP POST將它發送給PHP腳本。看到下面的日誌文件，我可以創建XML字符串並將其顯示在日誌文件中，但我無法將其傳遞給postXMLFeed方法。

我在做什麼錯？

-(IBAction)syncUp { 
[self createXMLFeed]; 
// [self postXMLFeed:XMLStr]; 
[self postXMLFeed]; 
} 


-(void)createXMLFeed{ 
//Fetch details from the database. 
NSFetchRequest *request = [[NSFetchRequest alloc] init]; 
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Tabrss" inManagedObjectContext:managedObjectContext]; 
[request setEntity:entity]; 
NSError *error; 
self.stories = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; 
[request release]; 

// Count the number of items in the array and display in the log. 
int arrayItemQuantity = [stories count]; 
NSLog(@"Array Quantity: %d", arrayItemQuantity); 

// Loop through the array and display the contents in the log. 
int i; 
for (i = 0; i < arrayItemQuantity; i++) 
{ 
    //NSString *XMLStr = [NSString stringWithFormat:@"<workout><id>%@</id><userid>%@</userid><walkid>%@</walkid><date>%@</date><distance>%@</distance><repeats>%@</repeats><type>%@</type><intensity>%@</intensity><comments>%@</comments><time>%@</time><weight>%@</weight><height>%@</height></workout>", 
    XMLStr = [NSString stringWithFormat:@"<workout><id>%@</id><userid>%@</userid><walkid>%@</walkid><date>%@</date><distance>%@</distance><repeats>%@</repeats><type>%@</type><intensity>%@</intensity><comments>%@</comments><time>%@</time><weight>%@</weight><height>%@</height></workout>", 
     [[stories objectAtIndex:i] valueForKey:@"ID"], 
     [[stories objectAtIndex:i] valueForKey:@"UserID"], 
     [[stories objectAtIndex:i] valueForKey:@"walkID"], 
     [[stories objectAtIndex:i] valueForKey:@"xDate"], 
     [[stories objectAtIndex:i] valueForKey:@"Distance"], 
     [[stories objectAtIndex:i] valueForKey:@"Repeats"], 
     [[stories objectAtIndex:i] valueForKey:@"Type"], 
     [[stories objectAtIndex:i] valueForKey:@"Intensity"], 
     [[stories objectAtIndex:i] valueForKey:@"Comments"], 
     [[stories objectAtIndex:i] valueForKey:@"xTime"], 
     [[stories objectAtIndex:i] valueForKey:@"Weight"], 
     [[stories objectAtIndex:i] valueForKey:@"Height"]]; 

    NSLog (@"XML Feed1: %@", XMLStr); 
} 
NSLog (@"XML Feed2: ", XMLStr); 

[stories release]; 

// Update log file. 
NSLog(@"Database read and XML feed created."); 
} 


//-(void)postXMLFeed:(NSString *)XMLStr 
-(void)postXMLFeed 
{ 
//XMLStr = @"<workout><id>1</id><userid>4</userid><walkid>20</walkid><date>2010-06-21 10:42:50</date><distance>12345</distance><repeats>1</repeats><type>StephenTesting</type><intensity>6.0</intensity><comments>testtesttest</comments><time>00:00:00</time><weight>65</weight><height>173</height></workout>"; 
//XMLStr = @"<xml><id>Hello World!</id></xml>"; 
NSLog (@"XML Feed3: ", XMLStr); 

NSURL *url = [NSURL URLWithString:@"http://192.168.1.200/stephen/sync_upload.php"]; 
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; 
[request setValue:@"text/xml" forHTTPHeaderField:@"Content-type"]; 
[request setHTTPMethod:@"POST"]; 
[request setHTTPBody:[XMLStr dataUsingEncoding:NSASCIIStringEncoding]]; 

NSURLResponse *response; 
NSError *error; 
response = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; 


// Update log file. 
NSLog(@"XML feed POSTED to website: ", XMLStr); 

//[super postXMLFeed]; 
} 

日誌文件：

2010-06-25 14:34:38.001 TAB RSS[2229:207] XML Feed: <workout><id>27 
    </id><userid>4 
    </userid><walkid> 
    </walkid><date>2010-06-21 10:42:25 
    </date><distance>1000 
    </distance><repeats>1 
    </repeats><type>Walking 
    </type><intensity>6.0 
    </intensity><comments>asdf 
    </comments><time>00:00:00 
    </time><weight>65 
    </weight><height>173 
</height></workout> 
2010-06-25 14:34:38.001 TAB RSS[2229:207] XML Feed: <workout><id>28 
    </id><userid>4 
    </userid><walkid> 
    </walkid><date>2010-06-21 10:45:05 
    </date><distance>152.4 
    </distance><repeats>1 
    </repeats><type>Hiking/Backpacking 
    </type><intensity>8.0 
    </intensity><comments>test 
    </comments><time>00:00:00 
    </time><weight>65 
    </weight><height>173 
</height></workout> 
2010-06-25 14:34:38.002 TAB RSS[2229:207] XML Feed: <workout><id>29 
    </id><userid>4 
    </userid><walkid> 
    </walkid><date>2010-06-21 12:31:28 
    </date><distance>0 
    </distance><repeats>1 
    </repeats><type>Aikido 
    </type><intensity>5.0 
    </intensity><comments>Nice training 
    </comments><time>01:30:00 
    </time><weight>65 
    </weight><height>173 
</height></workout> 
2010-06-25 14:34:38.002 TAB RSS[2229:207] XML Feed2: 
2010-06-25 14:34:38.003 TAB RSS[2229:207] Database read and XML feed created. 
2010-06-25 14:34:38.004 TAB RSS[2229:207] XML Feed3: 
(gdb) continue 
Current language: auto; currently objective-c 
2010-06-25 14:34:39.585 TAB RSS[2229:207] XML feed POSTED to website: 

Answer 1

stringWithFormat:是一個NSString類方法。它不保留它返回的字符串，所以它只保留其調用範圍的其餘部分。如果您要使用[[NSString alloc] initWithFormat:]，或者只需在XMLStr變量上調用retain，則應該可以在第二種方法中使用它。請記住在第二種方法結束時使用release字符串。

Answer 2

您分配XMLStr到autorealeased NSString 我將承擔爲NSString財產進行如下的XMLStr聲明：

@interface XMLWriter : NSObject { 
NSString *XMLStr; 
} 
@property (nonatomic, retain) NSString *XMLStr 
@end 

@implementation XMLWriter 
@synthesize XMLStr; 

在createXMLFeed變化：

XMLStr = [NSString .... 

要：

self.XMLStr = [NSString ....