Get data type of variable - objective-c

Question

#interface testing
#property NSString *email;
#property NSString *password;
#end
In another class , how to get data type of email, or password without defined the email and password.
NSArray *keys=[[NSArray alloc] init];
[keys addObject:#"email"];
testing *detail=[[testing alloc]init];
if([[detail valueForKey:keys[0]] isKindOfClass:[NSString class]])
{ NSLog("This is string class variable"); }
but it not enter the if condition

Answer 1

All you need to do to obtain the class of a property is
[email class];
[password class];
There are ways to test the object class as well using isKindOfClass: and isMemberOfClass: and even isSubclassOfClass:
You can use these in if statements like
if([email isKindOfClass:[NSString class]])
and/or
if([password isMemberOfClass:[NSString class]])
and/or
if([[email class] isSubclassOfClass:[NSString class]])
For a description of each these please read the Apple Documentation on NSObject class reference. and Apple Documentation on NSObject protocol reference
isSubclassOfClass:
Returns a Boolean value that indicates whether the receiving class is a subclass of, or identical to, a given class.
+ (BOOL)isSubclassOfClass:(Class)aClass
Parameters
aClass
A class object.
Return Value
YES if the receiving class is a subclass of—or identical to—aClass, otherwise NO.
Availability
Available in iOS 2.0 and later.
Declared In
objc/NSObject.h
isKindOfClass:
Returns a Boolean value that indicates whether the receiver is an instance of given class or an instance of any class that inherits from that class. (required)
- (BOOL)isKindOfClass:(Class)aClass
Parameters
aClass
A class object representing the Objective-C class to be tested.
Return Value
YES if the receiver is an instance of aClass or an instance of any class that inherits from aClass, otherwise NO.
Discussion
For example, in this code, isKindOfClass: would return YES because, in Foundation, the NSArchiver class inherits from NSCoder:
NSMutableData *myData = [NSMutableData dataWithCapacity:30];
id anArchiver = [[NSArchiver alloc] initForWritingWithMutableData:myData];
if ( [anArchiver isKindOfClass:[NSCoder class]] )
...
Be careful when using this method on objects represented by a class cluster. Because of the nature of class clusters, the object you get back may not always be the type you expected. If you call a method that returns a class cluster, the exact type returned by the method is the best indicator of what you can do with that object. For example, if a method returns a pointer to an NSArray object, you should not use this method to see if the array is mutable, as shown in the following code:
// DO NOT DO THIS!
if ([myArray isKindOfClass:[NSMutableArray class]])
{
// Modify the object
}
If you use such constructs in your code, you might think it is alright to modify an object that in reality should not be modified. Doing so might then create problems for other code that expected the object to remain unchanged.
If the receiver is a class object, this method returns YES if aClass is a Class object of the same type, NO otherwise.
Availability
Available in OS X v10.0 and later.
See Also
– isMemberOfClass:
Related Sample Code
QuickLookSketch
Sketch
Sketch+Accessibility
Declared In
objc/NSObject.h
isMemberOfClass:
Returns a Boolean value that indicates whether the receiver is an instance of a given class. (required)
- (BOOL)isMemberOfClass:(Class)aClass
Parameters
aClass
A class object representing the Objective-C class to be tested.
Return Value
YES if the receiver is an instance of aClass, otherwise NO.
Discussion
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]])
...
Class objects may be compiler-created objects but they still support the concept of membership. Thus, you can use this method to verify that the receiver is a specific Class object.
Availability
Available in OS X v10.0 and later.
See Also
– isKindOfClass:
Declared In
objc/NSObject.h
EDIT
When trying to access these properties in another class (Which isn't what you are asking in your question) do the following.
Testing *testingClassIVar = [[Testing alloc] init];
[testingClassIVar email];
[testingClassIVar password];
// to get the class type of these
[[testingClassIVar email] class];
[[testingClassIVar password] class];
EDIT 2
OMG just NO I don't even know what you are trying to do but it seems very wrong. NSArray doesn't respond to addObject: so this will crash your code. If you want to use addObject: then change the NSArray to NSMutableArray but unless you plan on using that array in a loop (If you are please specify I will not assume) then just access the property by using [detail email]
Change to this
testing *detail= [[testing alloc] init];
if([[detail email] isKindOfClass:[NSString class]]) {
NSLog("This is string class variable");
}