是否有iPhone的队列/ FIFO数据结构？

Before I roll my own Queue using NSMutableArray, I'd like to know if there is something more standard available. I don't see anything in the Apple docs, but I'll be surprised if there is not a Queue implementation from somewhere that folks are using. Java spoils me!

在我使用NSMutableArray滚动自己的Queue之前,我想知道是否有更多可用的标准。我没有在Apple文档中看到任何内容,但如果没有人们正在使用的某个地方的Queue实现,我会感到惊讶。 Java破坏了我!

6 个解决方案

#1

Implementing a queue based on NSMutableArray is pretty easy, it's probably under 50 lines of code.

实现基于NSMutableArray的队列非常简单,可能不到50行代码。

EDIT:

Found this with a quick google search:

通过快速谷歌搜索找到这个:

@interface Queue:NSObject {
   NSMutableArray* objects;
}
- (void)addObject:(id)object;
- (id)takeObject;
@end

@implementation Queue

- (id)init {
   if ((self = [super init])) {
       objects = [[NSMutableArray alloc] init];    
   }
   return self;
}

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

- (void)addObject:(id)object {
   [objects addObject:object];
}

- (id)takeObject  {
   id object = nil;
   if ([objects count] > 0) {
       object = [[[objects objectAtIndex:0] retain] autorelease];
       [objects removeObjectAtIndex:0];
   }
   return object;
}

@end

#2

Cocoa itself doesn't have a Queue class, and there's not a standard per se, but there are several options, one of which may best fit your needs. See this question (and my answer).

Cocoa本身没有Queue类,并且本身没有标准,但有几个选项,其中一个可能最适合您的需求。看到这个问题(和我的回答)。

Like you said, you can roll your own using NSMutableArray. If you just need a quick'n'dirty queue (and aren't worried about copying, encoding/decoding, enumeration, etc.) then the solution @Matt suggests is an easy approach. You should also consider adding queue methods to NSMutableArray via a category, which is nice in that your "queue" is also an array (so you can pass it for NSArray parameters), and you get all the NS(Mutable)Array functionality for free.

就像你说的,你可以使用NSMutableArray自己动手。如果你只需要一个quick'n'dirty队列(并且不担心复制,编码/解码,枚举等),那么@Matt建议的解决方案是一种简单的方法。您还应该考虑通过类别向NSMutableArray添加队列方法,这很好,因为您的“队列”也是一个数组(因此您可以为NSArray参数传递它),并且您可以免费获得所有NS(Mutable)数组功能。

If performance is important, I recommend using a structure more ideally suited for removing the first element. I wrote CHCircularBufferQueue for my own framework for this very reason. (Not trying to toot my own horn, just trying to save others some time.)

如果性能很重要,我建议使用更适合移除第一个元素的结构。出于这个原因,我为自己的框架编写了CHCircularBufferQueue。 (不要试图嘟嘟我自己的号角,只是试着节省一些时间。)

#3

I have made a category containing just the deque method, based on Matt Bridges code.

我基于Matt Bridges代码创建了一个仅包含deque方法的类别。

@interface NSMutableArray (ShiftExtension)
// returns the first element of self and removes it
-(id)shift;
@end

@implementation NSMutableArray (ShiftExtension)
-(id)shift {
    if([self count] < 1) return nil;
    id obj = [[[self objectAtIndex:0] retain] autorelease];
    [self removeObjectAtIndex:0];
    return obj;
}
@end

#4

You can use the STL queue from the C++ Standard Library.

您可以使用C ++标准库中的STL队列。

#5

Check out the STL priority queue. It requires zero lines of code and it's portable! What more could you want?

检查STL优先级队列。它需要零行代码,并且可移植!你还能想要什么?

#6

You could use the :lastObject method of NSArray. Here is an untested example:

您可以使用NSArray的:lastObject方法。这是一个未经测试的例子:

Queue.h

#import <Foundation/Foundation.h>

@interface Queue : NSObject

-(void)enqueue:(id)object;
-(id)dequeue;

@end

Queue.m

#import "Queue.h"

@interface Queue()

@property(nonatomic, strong) NSMutableArray *backingArray;

@end

@implementation Queue

-(id)init {
    self = [super init];

    if (self) {
        self.backingArray = [NSMutableArray array];
    }
    return self;
}

-(void)enqueue:(id<NSObject>)object {
    [self.backingArray addObject:object];
}

-(id)dequeue {
    id object = [self.backingArray lastObject];
    [self.backingArray removeObject:object];
    return object;
}

@end

#1