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Objective-C error EXC_BAD_ACCESS help please

开发者 https://www.devze.com 2023-01-12 05:47 出处:网络
I am currently using the pragmatic screencast on Objective-C to help me program in objective-c. I have a background in Java and C++, but I am having a very difficult time getting used to everything in

I am currently using the pragmatic screencast on Objective-C to help me program in objective-c. I have a background in Java and C++, but I am having a very difficult time getting used to everything in Ob开发者_开发问答jective(Mostly because I am not comfortable with the syntax). Below is the error I am receiving with all the code. I am also getting a warning in movie.m class as well: Wirtable atomic property 'title' cannot be pair a synthesized setter/getter with a user defined setter/getter

thanks for your help.

I am receive this error

Current language:  auto; currently objective-c
warning: Couldn't find class validation function, calling methods on uninitialized objects may deadlock your program.
Program received signal:  “EXC_BAD_ACCESS”.

I ran it through the debugger and the address of movie in the code below is in red

main.m

int main (int argc, const char * argv[]) {

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

Movie *movie = [[Movie alloc] initWithTitle:@"iron man"
                                andRating:5
                                    andYear:2008];

[movie play];
NSLog(@"our movie is %@", movie);

[pool drain];
return 0;}

Movie.h

    interface Movie : NSObject {
    NSString *title;
    int rating;
    int year;
}
- (id)initWithTitle:(NSString *)newTitle
          andRating:(int)newRating
            andYear:(int) year;

@property(assign) NSString *title;
@property(assign) int rating;
@property(assign) int year;
-(void) play;

@end

Movie.m

    #import "Movie.h"


@implementation Movie

@synthesize title;
@synthesize rating;
@synthesize year;
-(id)initWithTitle:(NSString *)newTitle
                    andRating:(int)newRating
           andYear:(int)newYear;
{

    self = [super init];
    if(nil != self){
        self.title = newTitle;
        self.rating = newRating;
        self.year = newYear;
    }
    return self;

}
-(NSString *) description{
    NSString *oldDescription = [super description];

    return [NSString stringWithFormat: @"%@ title =%@, rating =%d year=%@",
            oldDescription, self.title, self.rating, self.year];
}
- (void)setTitle:(NSString *)newTitle {
    title = [newTitle capitalizedString];
}
-(void) play {
    NSLog(@"Playing %@", self);
}


You use year=%@ when it should be year=%d.

Some more random thoughts:

You should retain or better even copy the title instead of assigning it.

The init method should be named

-(id)initWithTitle:(NSString *)aTitle
                    rating:(int)aRating
                    year:(int)aYear;

Don't forget a dealloc method then.


Your title property is an object type and so should in generally be either retain or copy -- in the case of NSString properties, it is traditional to use copy to avoid issues when you're passed an NSMutableString instead.

@property (copy) NSString* title;

Since you explicitly define the setter, you then need to implement this policy yourself, something like this:

- (void)setTitle:(NSString *)newTitle
{
    [title release];
    title = [[newTitle capitalizedString] copy];
}

You'll also need to include a dealloc method to clean up:

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