objective-c - NSArray 上的 IOS 类别导致 "instance message does not declare a method with selector"

Question

我正在尝试使用本文中描述的类别: http://iphonedevelopment.blogspot.com/2008/10/shuffling-arrays.html

我已经设置了以下内容:

//  NSArray+Shuffle.h
#import <Foundation/Foundation.h>
@interface NSArray (Shuffle)
-(NSArray *)shuffledArray;
@end


//  NSArray+Shuffle.m
#import "NSArray+Shuffle.h"
@implementation NSArray (Shuffle)
-(NSArray *)shuffledArray
{
    NSMutableArray *array = [NSMutableArray arrayWithCapacity:[self count]];
    NSMutableArray *copy = [self mutableCopy];
    while ([copy count] > 0)
    {
        int index = arc4random() % [copy count];
        id objectToMove = [copy objectAtIndex:index];
        [array addObject:objectToMove];
        [copy removeObjectAtIndex:index];
    }
// Using IOS 5 ARC
//    [copy release];
return array;
}
@end

然后在我想使用它的代码中，我导入了类别:

#import "NSArray+Shuffle.h"

然后，我尝试这样使用它:

    NSArray *orderedGallary = [[NSArray alloc] initWithObjects:
                 [NSDictionary dictionaryWithObjectsAndKeys:
                  @"Pic1", @"pageName",
                  [UIImage imageNamed:@"Pic1.jpg"],@"pageImage",
                  nil],
                 [NSDictionary dictionaryWithObjectsAndKeys:
                  @"Pic2", @"pageName",
                  [UIImage imageNamed:@"Pic2.jpg"],@"pageImage",
                  nil],

                 nil];   

    NSArray *shuffler = [[NSArray alloc] shuffledArray:orderedGallary];

    _pageData = [shuffler shuffledArray:orderedGallary];

但是，我收到以下编译器错误消息:

ModelController.m: error: Automatic Reference Counting Issue: Receiver type 'NSArray' for instance message does not declare a method with selector 'shuffledArray:'

有什么想法吗？

Answer 1

shuffledArray 是一种不带参数的方法，它不同于shuffledArray:，后者是带一个参数的方法。

看起来你的意思是:

NSArray* shuffled = [orderedGallery shuffledArray];

在这里，您将这条消息发送到您的原始数组，它返回一个经过混洗的新数组。