Question

Objective-C is really wierd, i can t get the hang of it... I have a NSstring that is losing it s value if I try to reassign it... Here s how I use it.. Can anyone tell me what am I doing wrong? it s happening at the assigning of the new value..

@interface PageViewController : UIViewController {

    NSString *mystring;
}

- (void)viewDidLoad {

    mystring=[ [NSString alloc] initWithString:@""];
}

-(void) function_definition:(NSString *) param {
.............
    mystring=param;
.........
}

Answer 1

最常见的情况是,你要把这一财产指定为:

@interface PageViewController : UIViewController {

    NSString *mystring;
}

@property (nonatomic, retain) NSString *mystring;

之后,你执行,

@synthesize mystring;

- (void)dealloc {
    [mystring release];
    [super dealloc];
}

最后,在你执行过程中,无论在什么地方,都利用:

[self setMystring:@"something"];

or

self.mystring = @"somethingelse";

如果你重新分配新的座椅,肯定会释放。它自动使用该财产。

self.mystring = [[[NSString alloc] initWithString:@"hello"] autorelease];

最后,在你的职责中:

-(void) function_definition:(NSString *) param {
.............
    self.mystring = param;
.........
}

Answer 2

这并非完全清楚你通过失去价值意味着什么,但我认为,这里的问题是:记忆管理——你需要

-(void) function_definition:(NSString *) param {
.............
    if (mystring != param) {
        [mystring release];
        mystring = [param retain];
    }
.........
}

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