In Objective-C, how do I test the object type?
When you want to differ between a superClass and the inheritedClass you can use:
if([myTestClass class] == [myInheritedClass class]){
NSLog(@"I'm the inheritedClass);
}
if([myTestClass class] == [mySuperClass class]){
NSLog(@"I'm the superClass);
}
Using - (BOOL)isKindOfClass:(Class)aClass
in this case would result in TRUE both times because the inheritedClass is also a kind of the superClass.
If your object is myObject
, and you want to test to see if it is an NSString
, the code would be:
[myObject isKindOfClass:[NSString class]]
Likewise, if you wanted to test myObject
for a UIImageView
:
[myObject isKindOfClass:[UIImageView class]]
Running a simple test, I thought I'd document what works and what doesn't. Often I see people checking to see if the object's class is a member of the other class or is equal to the other class.
For the line below, we have some poorly formed data that can be an NSArray
, an NSDictionary
or (null)
.
NSArray *hits = [[[myXML objectForKey: @"Answer"] objectForKey: @"hits"] objectForKey: @"Hit"];
These are the tests that were performed:
NSLog(@"%@", [hits class]);
if ([hits isMemberOfClass:[NSMutableArray class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isMemberOfClass:[NSMutableDictionary class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isMemberOfClass:[NSArray class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isMemberOfClass:[NSDictionary class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isKindOfClass:[NSMutableDictionary class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isKindOfClass:[NSDictionary class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isKindOfClass:[NSArray class]]) {
NSLog(@"%@", [hits class]);
}
if ([hits isKindOfClass:[NSMutableArray class]]) {
NSLog(@"%@", [hits class]);
}
isKindOfClass
worked rather well while isMemberOfClass
didn't.
You would probably use
- (BOOL)isKindOfClass:(Class)aClass
This is a method of NSObject
.
For more info check the NSObject
documentation.
This is how you use this.
BOOL test = [self isKindOfClass:[SomeClass class]];
You might also try doing somthing like this
for(id element in myArray)
{
NSLog(@"=======================================");
NSLog(@"Is of type: %@", [element className]);
NSLog(@"Is of type NSString?: %@", ([[element className] isMemberOfClass:[NSString class]])? @"Yes" : @"No");
NSLog(@"Is a kind of NSString: %@", ([[element classForCoder] isSubclassOfClass:[NSString class]])? @"Yes" : @"No");
}