In the below dictionary I want to write a condition for type class, Is there any way to identify the class type alone in the iteraction
NSDictionary *dictionary = [NSDictionary dictionaryWithKeysAndObjects:#"check",#"checkValue",#"webservice", [webservice class], #"list",#"listValue", nil, #"task", [task class], #"new", #"newValue", #"operation",[operation class]];
for(NSString *aKey in dictionary) {
if ([[dictionary valueForKey:aKey]) {
NSLog(#"Getting In");
}
}
Note :I want a single condition to check values [webservice class],[task class],[operation class]
Look up -isKindOfClass: and -isMemberOfClass:
if([object isKindOfClass:[AObjectClass class])
{
NSLog(#"object is of type AObjectClass");
}
See the Apple isKindOfClass: documentation.
- (BOOL)isMemberOfClass:(Class)aClass
this is what u seek probably.
For example, in this code, isMemberOfClass: would return NO:
NSMutableData *myData = [NSMutableData dataWithCapacity:30];
id anArchiver = [[NSArchiver alloc] initForWritingWithMutableData:myData];
if ([anArchiver isMemberOfClass:[NSCoder class]])
//something...
ref: http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Protocols/NSObject_Protocol/Reference/NSObject.html
Edit:
In NSDictionaries you will have to put Strings for keys. I suggest you convert the class to a string with NSStringFromClass([MyClass class]); and put that as a key.
The way you want to use the class as a key is impossible.
Found answer for my question in the below link
Check if object is Class type
NSDictionary *dictionary = [NSDictionary dictionaryWithKeysAndObjects:#"check",#"checkValue",#"webservice", [webservice class], #"list",#"listValue", nil, #"task", [task class], #"new", #"newValue", #"operation",[operation class]];
for(NSString *aKey in dictionary) {
if (class_isMetaClass(object_getClass(obj))) {
NSLog(#"Getting In");
}
}
Related
Why NSDictionary cannot be written?? I have checked the content of the dictionary: all the instances are of NSString and NSNumber. I checked permissions: a text file with the same name at the same path is written well. Of course, my dictionary is not empty.
NSString *file = ...
NSDictionary *dict = ...
// check dictionary keys
BOOL wrong = NO;
for (id num in [dict allKeys]) {
if (![num isKindOfClass:[NSNumber class]]) {
wrong = YES;
break;
}
}
if (wrong) {
NSLog(#"First");
}
// check dictionary values
wrong = NO;
for (id num in [dict allValues]) {
if (![num isKindOfClass:[NSString class]]) {
wrong = YES;
break;
}
}
if (wrong) {
NSLog(#"Second");
}
if (![dict writeToFile:file atomically:YES]) {
// 0k, let's try to create a text file
NSLog(#"Names writing error!");
[#"Something here... .. ." writeToFile:file atomically:YES encoding:NSUTF8StringEncoding error:nil];
}
Output: "Names writing error!"
Text file is created successfully.
Writing out a dictionary creates a property list, and according to the documentation all keys in a property list must be strings.
... and although NSDictionary and CFDictionary objects allow their keys to
be objects of any type, if the keys are not string objects, the
collections are not property-list objects.
NSNumber objects as keys are not supported.
As #vadian points out, you cannot write plist with numeric keys. But you can use NSKeyedArchiver:
NSURL *documents = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:false error:nil];
NSURL *fileURL = [documents URLByAppendingPathComponent:#"test.plist"];
// this will not work
NSDictionary *dictionary = #{#1: #"foo", #2: #"bar"};
BOOL success = [dictionary writeToFile:fileURL.path atomically:true];
NSLog(#"plist %#", success ? #"success" : #"failure");
// this will
fileURL = [documents URLByAppendingPathComponent:#"test.bplist"];
success = [NSKeyedArchiver archiveRootObject:dictionary toFile:fileURL.path];
NSLog(#"archive %#", success ? #"success" : #"failure");
And you can read it back with NSKeyedUnarchiver:
// to read it back
NSDictionary *dictionary2 = [NSKeyedUnarchiver unarchiveObjectWithFile:fileURL.path];
NSLog(#"dictionary2 = %#", dictionary2);
Note, you can do this with any class that conforms (and properly implements) NSCoding. Fortunately, NSDictionary conforms already. You have to make sure that any objects inside the dictionary, also conform (both NSString and NSNumber do). If you had a custom object in your dictionary, you'd have to make it properly conform yourself.
This is all described in the Archives and Serializations Programming Guide.
I'm a developer from Python world used to using exceptions. I found in many places that using exceptions is not so wise here, and did my best to convert to NSErrors when needed. but then I encounter this:
NSMutableArray *results;
for (NSDictionary *dict in dicts)
{
// Memory management code omitted
SomeModel *model = [[SomeModel alloc] init];
model.attr1 = [[dict objectForKey:#"key1"] integerValue];
model.attr2 = [[dict objectForKey:#"key2"] integerValue];
model.attr3 = [[dict objectForKey:#"key3"] integerValue];
model.attr4 = [[dict objectForKey:#"key4"] integerValue];
[results addObject:model];
}
with some of the objects in dict containing NSNull, which would result an "unrecognized selector" exception. In that case, I want to drop that datum completely. My first instinct is to wrap the whole content of the for block into a #try-#catch block:
NSMutableArray *results;
for (NSDictionary *dict in dicts)
{
#try
{
SomeModel *model = [[SomeModel alloc] init];
model.attr1 = [[dict objectForKey:#"key1"] integerValue];
model.attr2 = [[dict objectForKey:#"key2"] integerValue];
model.attr3 = [[dict objectForKey:#"key3"] integerValue];
model.attr4 = [[dict objectForKey:#"key4"] integerValue];
[results addObject:model];
}
#catch(NSException *exception)
{
// Do something
}
}
But is this a good approach? I can't come up with a solution without repeating checks on each variable, which is really ugly IMO. Hopefully there are alternatives to this that haven't occur to me. Thanks in advance.
The proper Objective-C way to do this would be:
for (NSDictionary *dict in dicts)
{
if (! [dict isKindOfClass:[NSDictionary class]])
continue;
// ...
}
Testing if a receiver can respond to a message before sending it is a typical pattern in Objective-C.
Also, take note that exceptions in Objective-C are always a programmer error and are not used for normal execution flow.
Many people use a category on NSDictionary for these cases:
- (id)safeObjectForKey:(id)aKey
{
id obj = [self objectForKey:aKey];
if ([obj isKindOfClass:[NSNull class]])
{
return nil;
}
return obj;
}
You still need to make sure, that your dict is an actual dictionary instance.
In the end I decided to solve the problem using KVC. Something like this:
- (id)initWithPropertyDictionary:(NSDictionary *)dict
lookUpTable:(NSDictionary *)keyToProperty
{
self = [self init];
for (NSString *key in dict)
{
NSString *propertyName;
if ([keyToProperty objectForKey:key])
propertyName = [keyToProperty objectForKey:key];
else
propertyName = key;
if ([[dict objectForKey:key] isKindOfClass:[NSNull class]])
{
[self release];
return nil;
}
else
{
[self setValue:[dict objectForKey:key] forKey:propertyName];
}
}
}
The setback of this resolution is that I'll have to use NSNumber for my properties, but for JSON data there is really no distinction between floating numbers and integers, so this is fine.
And if you really want primitive types, you can couple this method with custom setters that converts those NSNumbers into appropriate types.
With this, all you need to do is check for nil before adding the object into the array. Much cleaner everywhere except the model class.
Thanks to jaydee3 for inspiring me to focus on changing the model class.
I want to see objects classes of my dictionary in console log. As for standard NSObject subclasses, I override -(NSString*) description in category:
-(NSString*) description
{
NSMutableString* desc = [NSMutableString stringWithFormat: #"<%# 0x%08x>\nobjects count: %ld", [self class], (uint)self, [self count]];
for (id key in [self allKeys])
[desc appendFormat: #"\n%# = %# (%#)", key, [self objectForKey: key], [[self objectForKey: key] class]];
return desc;
}
It works, but only for top-level NSDictionary object (if the object has dictionaries in children they are logged bypassing description method). So NSDictionary prints its children objects in some way without calling description on them...
Is there an approach to log these children dictionaries through my description method?
PS: In practical situation I want to find an object in dictionary that can't be saved to plist. Maybe there is another solution, I would be thankful for that too.
You can write a recursive description method:
// Private Methods
#interface MyClass ()
- (NSString *)_description:(id)object;
#end
...
- (NSString *)_description:(id)object
{
if ([object isKindOfClass:[NSDictionary class]])
{
NSDictionary *dict = (NSDictionary *)object;
NSMutableString *desc = [NSMutableString stringWithFormat: #"<%# %p>\nobjects count: %ld", [dict class], dict, [dict count]];
for (id key in [dict allKeys])
{
[desc appendFormat: #"\n%# = %# (%#)", key, [self _description:[objectForKey: key]], [[self objectForKey: key] class]];
return desc;
}
}
else
{
return [(NSObject *)object description];
}
}
- (NSString *)description
{
return [self _description:self];
}
You'll probably want to pass an incrementing indentation counter so you can format the child objects better, but you should get the idea.
I want to be able to take an object and write out all its properties to a PLIST. I got so far with this:
// Get the properties of the parent class
NSMutableArray *contentViewPropertyNames = [self propertyNamesOfObject:[contentView superclass]];
// Add the properties of the content view class
[contentViewPropertyNames addObjectsFromArray:[self propertyNamesOfObject:contentView]];
// Get the values of the keys for both the parent class and the class itself
NSDictionary *keyValuesOfProperties = [contentView dictionaryWithValuesForKeys:contentViewPropertyNames];
// Write the dictionary to a PLIST
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *pathAndFileName = [documentsDirectory stringByAppendingPathComponent:[dataFileName stringByAppendingString:#".plist"]];
[keyValuesOfProperties writeToFile:pathAndFileName atomically:YES];
All good, except I can't write this to a PLIST because it contains some properties that are not compliant with PLISTs, so writeToFile:atomically: fails and returns NO.
Is there a good way to serialize only those properties that are serailizable into a PLIST or modify the base class of my objects to make this work?
I realise I could archive to a binary file no problem with NSCoding however I need to be able to transfer the output between a MacOS application and an iOS app, so need to go via an intermediate, platform independent format.
Of course I could be missing the point entirely, if I have please do tell, and as always, any help is useful.
Best regards
Dave
P.S.
Here is my method to get the property names of an object:
- (NSMutableArray *)propertyNamesOfObject:(id)object {
NSMutableArray *propertyNames = nil;
unsigned int count, i;
objc_property_t *properties = class_copyPropertyList([object class], &count);
if (count > 0) {
propertyNames = [[[NSMutableArray alloc] init] autorelease];
for(i = 0; i < count; i++) {
objc_property_t property = properties[i];
const char *propName = property_getName(property);
if(propName) {
NSString *propertyName = [NSString stringWithCString:propName encoding:NSUTF8StringEncoding];
[propertyNames addObject:propertyName];
}
}
}
free(properties);
return propertyNames;
}
See if you can apply this function I recently wrote in a similar situation:
// Property list compatible types: NSString, NSData, NSArray, or NSDictionary */
- (BOOL)isPlistCompatibleDictionary:(NSDictionary *)dict {
NSSet *plistClasses = [NSSet setWithObjects:[NSString class], [NSData class],
[NSArray class], [NSDictionary class], [NSDate class],
[NSNumber class], nil];
BOOL compatible = YES;
NSArray *keys = [dict allKeys];
for (id key in keys) {
id obj = [dict objectForKey:key];
if (![plistClasses containsObject:[obj class]]) {
NSLog(#"not plist compatible: %#", [obj class]);
compatible = NO;
break;
}
}
return compatible;
}
I have a method which returns me a nsdictionary with certain keys and values. i need to change the key names from the dictionary to a new key name but the values need to be same for that key,but i am stuck here.need help
This method will only work with a mutable dictionary. It doesn't check what should be done if the new key already exists.
You can get a mutable dictionary of a immutable by calling mutableCopy on it.
- (void)exchangeKey:(NSString *)aKey withKey:(NSString *)aNewKey inMutableDictionary:(NSMutableDictionary *)aDict
{
if (![aKey isEqualToString:aNewKey]) {
id objectToPreserve = [aDict objectForKey:aKey];
[aDict setObject:objectToPreserve forKey:aNewKey];
[aDict removeObjectForKey:aKey];
}
}
You can't change anything in an NSDictionary, since it is read only.
How about loop through the dictionary and create a new NSMutableDictionary with the new key names ?
Could you not add a new key-value pair using the old value, and then remove the old key-value pair?
This would only work on an NSMutableDictionary. NSDictionarys are not designed to be changed once they have been created.
To change specific key to new key, I have written a recursive method for Category Class.
- (NSMutableDictionary*)replaceKeyName:(NSString *)old_key with:(NSString )new_key {
NSMutableDictionary dict = [NSMutableDictionary dictionaryWithDictionary: self];
NSMutableArray *keys = [[dict allKeys] mutableCopy];
for (NSString key in keys) {
if ([key isEqualToString:old_key]) {
id val = [self objectForKey:key];
[dict removeObjectForKey:key];
[dict setValue:val forKey:new_key];
return dict;
} else {
const id object = [dict objectForKey: key];
if ([object isKindOfClass:[NSDictionary class]]) {
[dict setObject:[dict replaceKeyName:old_key with:new_key] forKey:key];
} else if ([object isKindOfClass:[NSArray class]]){
if (object && [(NSArray)object count] > 0) {
NSMutableArray *arr_temp = [[NSMutableArray alloc] init];
for (NSDictionary *temp_dict in object) {
NSDictionary *temp = [temp_dict replaceKeyName:old_key with:new_key];
[arr_temp addObject:temp];
}
[dict setValue:arr_temp forKey:key];
}
}
}
}
return dict;
}