How to edit an XML file in ios5.1 ?

How large is your source XML? If it easily fits in available RAM on the device, consider using an XML DOM. I use the XML DOM in Google's GData Objective-C library because Cocoa doesn't include an XML DOM (NSXMLDocument) for iOS. If you don't need other GData APIs, you only need to include GDataXMLNode.h and .m in your project.

http://code.google.com/p/gdata-objectivec-client/

You could either: (1) Continue to use SAX (NSXMLParser) to read your source file, then create the three parts using GDataXMLDocument, or (2) Read your source file into GDataXMLDocument, then separate the nodes. The latter would be easier.

This article walks through an example of reading and writing with GDataXMLDocument.

http://www.raywenderlich.com/725/how-to-read-and-write-xml-documents-with-gdatax ml

I don't know what your model is but if I assume a straighforward tree-structured model PresetInfo > Modality > Body, this code is the design pattern I usually use. If you don't actually need to load a model, but instead just extract a specific data element, look at the XPath query in PresetInfo.parseXmlElement, and how I get attribute and element values in the other parseXmlElements.

The model interface. I used arrays for the lists, if you need keyed access to list elements, you could use dictionaries. The top-level class PresetInfo contains methods to read the XML from a file.

@interface ModelBase : NSObject

- (id)initWithXmlElement:(GDataXMLElement *)element;

- (void)parseXmlElement:(GDataXMLElement *)element;

@end

@interface PresetInfo : ModelBase

@property NSMutableArray *modalities;

- (id)initWithPath:(NSString *)path;

- (id)initWithXmlString:(NSString *)xmlString;

@end

@interface Modality : ModelBase

@propertyNSString *type;

@propertyNSMutableArray *bodies;

@end

@interface Body : ModelBase

@propertyNSString *part;

@propertyNSInteger ww;

@propertyNSInteger wl;

@end

The model implementation.

@implementation ModelBase

- (id)initWithXmlElement:(GDataXMLElement *)element

{

if (self = [self init]) {

[self parseXmlElement:element];

}

returnself;

}

- (void)parseXmlElement:(GDataXMLElement *)element {

[NSExceptionraise:NSInternalInconsistencyExceptionformat:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
// Objective-C has no abstract methods

}

@end

@implementation PresetInfo

- (id)init

{

if (self = [super init]) {

self.modalities = [[NSMutableArray alloc] init];

}

returnself;

}

- (id)initWithPath:(NSString *)path

{

NSError *error = nil;

NSStringEncoding *usedEncoding = nil;

NSString *xmlString = [NSString stringWithContentsOfFile:path usedEncoding:usedEncoding error:&error];

if (!xmlString)

NSLog(@"Error reading XML file: %@", [error localizedDescription]);

return [self initWithXmlString:xmlString];

}

- (id)initWithXmlString:(NSString *)xmlString

{

NSError *error = nil;

GDataXMLDocument *xmlDoc = [[GDataXMLDocument alloc] initWithXMLString:xmlString options:0 error:&error];

if (!xmlDoc)

NSLog(@"Error creating XML document: %@", [error localizedDescription]);

return [selfinitWithXmlElement:xmlDoc.rootElement];

}

- (void)parseXmlElement:(GDataXMLElement *)element

{

NSError *error = nil;

NSArray *nodes = [element nodesForXPath:@"presetinfo/modality" error:&error];

if (!nodes) {

NSLog(@"Response not found: %@", [error localizedDescription]);

return;

}

for (GDataXMLElement *element in nodes)

[self.modalities addObject:[[Modality alloc] initWithXmlElement:element]];

}

@end

@implementation Modality

- (id)init

{

if (self = [super init]) {

self.bodies = [[NSMutableArray alloc] init];

}

returnself;

}

- (void)parseXmlElement:(GDataXMLElement *)element {

GDataXMLNode *node = [element attributeForName:@"type"];

if (node) self.type = node.stringValue;

NSArray *nodes = [element elementsForName:@"body"];

for (GDataXMLElement *element in nodes)

[self.bodies addObject:[[Body alloc] initWithXmlElement:element]];

}

@end

@implementation Body

- (void)parseXmlElement:(GDataXMLElement *)element {

GDataXMLNode *node = [element attributeForName:@"PART"];

if (node) self.part = node.stringValue;

node = [element attributeForName:@"WW"];

if (node) self.ww = [node.stringValue integerValue];

node = [element attributeForName:@"WL"];

if (node) self.wl = [node.stringValue integerValue];

}

@end

Example of loading your XML into the model and showing the data. This assumes the containing class (for example a view controller) has a property PresetInfo *presetInfo and the XML you posted is in a file presetinfo.xml.

// load the XML into the model

NSString *path = [[NSBundlemainBundle] pathForResource:@"presetinfo"ofType:@"xml"];

self.presetInfo = [[PresetInfoalloc] initWithPath:path];

// verify the model loaded correctly

for (Modality *modality inself.presetInfo.modalities) {

for (Body *body in modality.bodies) {

NSLog(@"Modality Type = %@; Body Part = %@; WW = %d; WL = %d", modality.type, body.part, body.ww, body.wl);

}

}