NSKeyValueCoding Informal Protocol

NSKeyValueCoding Overview

# NSKeyValueCoding

An informal protocol on NSObject. It provides an indirect way of setting values by key (property / iVar name) without using accessors or iVar access.

## Getting Values

```
- valueForKey:
- valueForKeyPath:
- dictionaryWithValuesForKeys:
- valueForUndefinedKey:
- mutableArrayValueForKey:
- mutableArrayValueForKeyPath:
- mutableSetValueForKey:
- mutableSetValueForKeyPath:
- mutableOrderedSetValueForKey:
- mutableOrderedSetValueForKeyPath:
```

## Setting Values

```
- setValueForKey:
- setValueForKeyPath:
- setNilValueForKey:
- setValuesForKeysWithDictionary:
- setValue;forUndefinedKey:
```

## Changing Default Behavior

```
+ accessInstanceVariablesDirectly
```

## Validation

```
- validateValue:forKey:error:
- validateValue:forKeyPath:error:
```
## Also Contains

The protocol also contains string constants for exceptions, error keys, and collection operators