三种集合类来收集cocoa对象(NSObject对象)：

NSArray 用于对象有序集合(相当于是数组)

NSSet 用于对象无序集合

NSDictionary用于键值映射

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;

- (id)objectAtIndex:(int)index; // NSString *s1=[[myarray objectAtIndex: 0];

- (void)makeObjectsPerformSelector:(SEL)aSelector;

- (NSArray *)sortedArrayUsingSelector:(SEL)aSelector;

- (id)lastObject; // returns nil if there are no objects in the array (convenient)

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];

//- (unsigned) Count;数组所包含对象个数;

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

//- (id) objectAtIndex: (unsigned int) index;获取指定索引处的对象;

NSLog(@"self.dataArray cound 2:%@",[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];

//Copy and sort

//NSMutableArray *newArray = [[NSMutableArray alloc] init];

NSArray *oldArray = [NSArray arrayWithObjects:

NSMutableArray

Mutable version of NSArray.

- (void)addObject:(id)anObject;

- (void)insertObject:(id)anObject atIndex:(int)index;

- (void)removeObjectAtIndex:(int)index;

- (void)removeAllObjects;

-----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

key-value, key-value, ..... 一系列键值对。

key(键)在整个dictionary是唯一的，通过key可以查询其对应的一个或多个value(值)。

Hash table. Look up objects using a key to get a value.

Immutable. You cannot add or remove objects to it once it’s created.

Keys are objects which must implement. Keys are usually NSString objects.

- (NSUInteger)hash & - (BOOL)isEqual:(NSObject *)obj

Important methods:

+ dictionaryWithObjectsAndKeys: (id)firstObject, ...;

- (int)count;

- (id)objectForKey:(id)key;

- (NSArray *)allKeys;

- (NSArray *)allValues;

-----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 *)dictionary;

- (void)setObject:(id)anObject forKey:(id)key;

- (void)removeObjectForKey:(id)key;

- (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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