IOS中数组的使用(NSArray, NSSet, NSDictionary)

一、Foundation framework中用于收集cocoa对象（NSObject对象）的三种集合分别是：

NSArray 用于对象有序集合（数组）
NSSet 用于对象无序集合（集合）

NSDictionary用于键值映射（字典）

以上三种集合类是不可变的（一旦初始化后，就不能改变）

以下是对应的三种可变集合类(这三种可变集合类是对应上面三种集合类的子类)：

NSMutableArray
NSMutableSet
NSMutableDictionary

注：这些集合类只能收集cocoa对象（NSOjbect对象），如果想保存一些原始的C数据（例如，int, float, double, BOOL等），则需要将这些原始的C数据封装成NSNumber类型的，NSNumber对象是cocoa对象，可以被保存在集合类中。

=================== NSArray ====================

Ordered collection of objects. Immutable(you cannot add or remove objects to it once it’s created)
Important methods:
+ (id)arrayWithObjects:(id)firstObject, ...; // nil terminated
- (int)count; // 得到array中的对象个数
- (id)objectAtIndex:(int)index; // 得到索引为i的对象

- (BOOL)containsObject:(id)anObject; // 当anObject出现在array中，则返回yes（实际是通过isEqual:方法来判断）

- (unsigned)indexOfObject:(id)anObject; // 查找array中的anObject,并返回其最小索引值。没找到返回NSNotFound.

- (void)makeObjectsPerformSelector:(SEL)aSelector;

- (NSArray *)sortedArrayUsingSelector:(SEL)aSelector;
- (id)lastObject; // 得到array中最后一个对象。如果array中没有任何对象存在，则返回nil
注：
类方法arrayWithObjects 可以创建an autoreleased NSArray of the items.例如
@implementation MyObject
- (NSArray *)coolCats {
return [NSArray arrayWithObjects:@“Steve”, @“Ankush”, @“Sean”, nil];
}
@end
Other convenient create with methods (all return autoreleased objects):
[NSString stringWithFormat:@“Meaning of %@ is %d”, @“life”, 42];
[NSDictionary dictionaryWithObjectsAndKeys:ankush, @“TA”, janestudent, @“Student”, nil];
[NSArray arrayWithContentsOfFile:(NSString *)path];
-----创建数组 -----
NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];

self.dataArray = array;
[array release];

NSLog(@"self.dataArray count is:%d",[self.dataArray count]);

NSLog(@"self.dataArray index 2 is:%@",[self.dataArray objectAtIndex:2]);

------ 从一个数组拷贝数据到另一数组(可变数级) -------

//arrayWithArray:
NSArray *array1 = [[NSArray alloc] init];
NSMutableArray *MutableArray = [[NSMutableArray alloc] init];
NSArray *array = [NSArray arrayWithObjects:@"a",@"b",@"c",nil];
NSLog(@"array:%@",array);
MutableArray = [NSMutableArray arrayWithArray:array];
NSLog(@"MutableArray:%@",MutableArray);

array1 = [NSArray arrayWithArray:array];
NSLog(@"array1:%@",array1);

//Copy

//id obj;
NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];

NSLog(@"oldArray:%@",oldArray);
for(int i = 0; i < [oldArray count]; i++) {
obj = [[oldArray objectAtIndex:i] copy];
[newArray addObject: obj];
}

NSLog(@"newArray:%@", newArray);
[newArray release];

//快速枚举
NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);

for(id obj in oldArray)
{
[newArray addObject: obj];
}

NSLog(@"newArray:%@", newArray);
[newArray release];

//Deep copy

NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
newArray = (NSMutableArray*)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (CFPropertyListRef)oldArray, kCFPropertyListMutableContainers);
NSLog(@"newArray:%@", newArray);
[newArray release];

=================== [b]NSMutableArray [/b]====================
Mutable version of NSArray.
- (void)addObject:(id)anObject; // 在array最后添加anObject, 添加nil是非法的.
- (void)addObjectsFromArray:(NSArray *)otherArray; //在array最后把otherArray中的对象依次添加进去。

- (void)insertObject:(id)anObject atIndex:(int)index; //在索引index处插入anObject, 若index被占用，会把之后的object向后移。

- (void)removeObjectAtIndex:(int)index; //删除index处的对象，后面的对象依次向前移。

- (void)removeObject:(id)anObject; // 删除所有和anObject相等的对象，同样使用isEqual:作为相等比较方法.
- (void)removeAllObjects;

注：我们不能把nil加到array中。但有时候我们真想给array加一个空的对象，可以使用NSNull来做这件事。如：

[myArray addObject:[NSNull null]];

-----给数组分配容量-----
//NSArray *array;
array = [NSMutableArray arrayWithCapacity:20];

-----在数组末尾添加对象-----
//- (void) addObject: (id) anObject;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil];
[array addObject:@"Four"];
NSLog(@"array:%@",array);

-----删除数组中指定索引处对象-----
//-(void) removeObjectAtIndex: (unsigned) index;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil];
[array removeObjectAtIndex:1];
NSLog(@"array:%@",array);

----- 数组枚举-----
//1、- (NSEnumerator *)objectEnumerator; //从前向后
NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array objectEnumerator];

id thingie;
while (thingie = [enumerator nextObject]) {
NSLog(@"thingie:%@",thingie);
}
//2、- (NSEnumerator *)reverseObjectEnumerator; //从后向前
NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array reverseObjectEnumerator];

id object;
while (object = [enumerator nextObject]) {
NSLog(@"object:%@",object);
}
//3、快速枚举
NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil];
for(NSString *string in array) {
NSLog(@"string:%@",string);
}

----- NSValue（对任何对象进行包装）-----
//将NSRect放入NSArray中
NSMutableArray *array = [[NSMutableArray alloc] init];
NSValue *value;
CGRect rect = CGRectMake(0, 0, 320, 480);
value = [NSValue valueWithBytes:&rect objCType:@encode(CGRect)];
[array addObject:value];
NSLog(@"array:%@",array);
//从Array中 提取
value = [array objectAtIndex:0];
[value getValue:&rect];
NSLog(@"value:%@",value);

----★使用NSMutableArray要防止内存泄露★------
NSObject* p1 = [[NSObject alloc] init];
NSObject* p2 = [[NSObject alloc] init];
NSMutableArray* objectsArray = [[NSMutableArray alloc] init];

[objectsArray addObject:p1];
NSLog(@"p1 count:%d", [p1 retainCount]);//输出 2，也就是执行追加对象后，对象的计数器也被加1
//[p1 release];
//NSLog(@"p1 count:%d", [p1 retainCount]);

//同样做数组替换时
[objectsArray replaceObjectAtIndex:0 withObject:p2];
NSLog(@"p2 count:%d", [p2 retainCount]);//输出 2，同样也是2
NSLog(@"p1 count:%d", [p1 retainCount]);//输出 1，对象p1仍然存在
//[p2 release];
//NSLog(@"p2 count:%d", [p2 retainCount]);

//执行清空数组
[objectsArray removeAllObjects];
NSLog(@"p2 count:%d", [p2 retainCount]);//输出 1，对象p2仍然存在
//[p2 release];

由此可知，每次执行上面的数组操作后，要执行对象release，如上面注释中的语句，才能保证内存不泄露。

NSSet
Unordered collection of objects.
Immutable. You cannot add or remove objects to it once it’s created.
Important methods:
+ setWithObjects:(id)firstObj, ...; // nil terminated

- (int)count;
- (BOOL)containsObject:(id)anObject;
- (id)anyObject;
- (void)makeObjectsPerformSelector:(SEL)aSelector;
- (id)member:(id)anObject; // uses isEqual: and returns a matching object (if any)

NSMutableSet
Mutable version of NSSet.
+ (NSMutableSet *)set;
- (void)addObject:(id)anObject;
- (void)removeObject:(id)anObject;
- (void)removeAllObjects;
- (void)unionSet:(NSSet *)otherSet;
- (void)minusSet:(NSSet *)otherSet;
- (void)intersectSet:(NSSet *)otherSet;

NSDictionary

一个dictionary就是key-value对的集合。 key是字符串（NSString），value是对象指针。
key在整个dictionary是唯一的。通过方法objectForKey：来获得对应于某个key的一个或多个value（值）。
NSDictionary在创建时，其中所有的key和对应的value都存在了。你可以访问其内容，但不可以修改。
dictionary使用hash表来实现，所以查找速度很快。
- (NSUInteger)hash & - (BOOL)isEqual:(NSObject *)obj
Important methods:
+ dictionaryWithObjectsAndKeys: (id)firstObject, ...;
- (int)count; // 返回有多少对key-value
- (id)objectForKey:(id)key; //返回和key相关联的value。 如果没有和key相关联的value，则返回nil。
- (NSArray *)allKeys; // 返回一个包含所有key的array
- (NSArray *)allValues;
- NSEnumerator *)keyEnumerator; //这个方法是从一个 dictionary 中得到一个 key 的迭代器.

Enumerators 也就是 iterators 或 enumerations.我们可以使用它来一步一步迭代出集合中的所 有成员.

下面是我们可能使用它来列举所有的 key- ‐vaule 对
NSEnumerator *e = [myDict keyEnumerator];

for (NSString *s in e) {

NSLog(@"key is %@, value is %@", s, [myDict objectForKey:s]);

}

注：NSArray 也有一个类似的方法得到 array 的成员迭代 器 : objectEnumerator

-----创建字典 -----
- (id) initWithObjectsAndKeys;
NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];
NSString *string = [dictionary objectForKey:@"One"];
NSLog(@"string:%@",string);
NSLog(@"dictionary:%@",dictionary);
[dictionary release];

NSMutableDictionary
Mutable version of NSDictionary.
NSMutableDictionary是NSDictionary的子类。创建后，允许用户添加和删除key和value。
+ (NSMutableDictionary *)dictionary; // 创建一个空的dictionary
- (void)setObject:(id)anObject forKey:(id)key; // 使用key和anObject组成一条记录添加到dictionary中
// 如果key已存在，则会先移除旧的key-value，然后再添加新的key-value。
- (void)removeObjectForKey:(id)key; // 从dictionary中删除一条记录，key以及和它对应的value
- (void)removeAllObjects;
- (void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;
-----创建可变字典 -----
//创建
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
//添加字典
[dictionary setObject:@"One" forKey:@"1"];
[dictionary setObject:@"Two" forKey:@"2"];
[dictionary setObject:@"Three" forKey:@"3"];
[dictionary setObject:@"Four" forKey:@"4"];
NSLog(@"dictionary:%@",dictionary);
//删除指定的字典
[dictionary removeObjectForKey:@"3"];
NSLog(@"dictionary:%@",dictionary);

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