Get NSDictionary with variable names as keys - ios

Question

Say I have n variables
NSNumber* A = #(1);
NSNumber* B = #(2);
NSNumber* C = #(3);
NSNumber* D = #(4);
NSNumber* E = #(5);
...
I need a dictionary like
{#"A":#(1), #"B":#(2), #"C":#(3), #"D":#(4), ... }
One can imagine a more cumbersome example that would be tedious to type out
I think saw a C style function for it but I can't remember. Something like NSDictionaryForVariables()

Answer 1

The C preprocessor macro (not a function) you're looking for is NSDictionaryOfVariableBindings. However, outside of Auto Layout (and, debatably, even there), it's not really a great idea to be setting up dependencies between runtime and compile-time identifiers like that.
Depending on what you're trying to actually accomplish, Key-Value Coding might be a better solution.

Answer 2

It's not a good approach you may find another way to solve your issue but if you want to have an idea about your requested solution here here my try
Our properties
#interface TestyViewController ()
#property (nonatomic) NSNumber* a;
#property (nonatomic) NSNumber* b;
#property (nonatomic) NSNumber* c;
#property (nonatomic) NSNumber* d;
#end
Set the values
- (void)viewDidLoad {
[super viewDidLoad];
self.a=#(1);
self.b=#(2);
self.c=#(3);
self.d=#(4);
}
Get our instance variables
-(NSArray *)propertyNames{
unsigned int propertyCount = 0;
objc_property_t * properties = class_copyPropertyList([self class], &propertyCount);
NSMutableArray * propertyNames = [NSMutableArray array];
for (unsigned int i = 0; i < propertyCount; ++i) {
objc_property_t property = properties[i];
const char * name = property_getName(property);
[propertyNames addObject:[NSString stringWithUTF8String:name]];
}
free(properties);
return propertyNames;
}
Create the dictionary
- (IBAction)buttonClicked:(id)sender
{
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
for (NSString* varName in [self propertyNames])
{
[dict setObject:[self valueForKey:varName] forKey:varName];
}
NSLog(#"%#",dict);
}
result
2015-07-15 20:30:56.546 TestC[879:27973] {
a = 1;
b = 2;
c = 3;
d = 4;
}