Objective C - Lvalue required as left operand of assignment

I get the error (L开发者_运维技巧value required as left operand of assignment) for this code:

[[addAlertViewController alertsArray] = [NSMutableArray arrayWithObjects:nil] retain];

How can I fix it?

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Knowing what an lvalue and rvalue will help when deciphering compiler warnings. A lvalue is something that will be assigned and a rvalue is something that can do the assigning. More info on wikipedia

An rvalue can also be a lvalue, like in the case of a = b = c (where c is an rvalue to lvalue b, but then b is a rvalue to the lvalue a).

anytime you see "lvalue required" then look on the left of the = operator, there is an error there.

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The appropriate Code is as follows:

[addAlertViewController setAlertsArray:[NSMutableArray arrayWithObjects:nil]];

Be careful that you have declared in your @interface of addAlertViewController's Class:

@property (nonatomic, retain) NSMutableArray *alertsArray;

And in your implementation file

@synthesize alertsArray;

And.. I'll agree with @taskinoor, RTFM.