The difference between SetValue and SetObject

SetValue Forkey and SetObject forkey are often used when using nsmutabledictionary, and they can often be used interactively.

Definition of 1.setValue Forkey

@interface Nsmutabledictionary (nskeyvaluecoding)

/* Send-setobject:forkey:to the receiver, unless the value is nil, in which case Send-removeobject:forkey:.

*/

-(void) SetValue: (ID) value Forkey: (NSString *) key;

@end

Extension Nsmutabledictionary A category, the above comment is very clear, send setobject:forkey to the receiver, that is, call Setobject:forkey method

Unless value is nil, the method is called Removeobject:forkey

Definition of 2.setobject:forkey

@interface nsmutabledictionary:nsdictionary

-(void) Removeobjectforkey: (id) akey;

-(void) SetObject: (ID) anobject Forkey: (ID <nscopying>) Akey;

@end

Note: The object of key in Setobject:forkey is an ID type, not a nsstring, but we often use nsstring.

The difference between the two:

1, Setobject:forkey value is not able to nil, or will error

The value in Setvalue:forkey can be null, but when value is empty, the Removeobject:forkey method is called automatically

2, setvakue:forkey key parameter can only be nsstring type, and Setobjecct:forkey can be any type

Attention:

1, [imagedictionarysetobject:[NSNullnull]forkey:indexnumber];

[NSNull null] Represents an empty object, not nil, note this

2, Setobject:forkey: When key is the NSNumber object, the following:

[imagedictionarysetobject:obj forkey:[nsnumber numberwithint:10];

The difference mentioned above is for the caller to be dictionary.

Setobject:forkey: Method Nsmutabledictionary Peculiar, and

Setvalue:forkey: Method is the Main method of KVC (key-value encoding).

When Setvalue:forkey: The method caller is an object:

Setvalue:forkey: The method is created in the NSObject object, which means that all OC objects have this method, so they can be used in any class.

For example, use:

SomeClass *someobj = [[SomeClass alloc] init];

[Someobj setvalue:self forkey:@ "Delegate"];

Object Someobj Set the value of his delegate property to the current class, and of course the object calling this method must have a delegate property to set, or the call will not be effective

The difference between SetValue and setobject