----- 給數組分配容量 -----
??? //NSArray *array;
? ? array = [NSMutableArray? arrayWithCapacity :20];

----- 在數組末尾添加對象 -----
??? //- (void) addObject: (id) anObject;
? ? //NSMutableArray *array = [NSMutableArray? arrayWithObjects :@"One",@"Two",@"Three",nil];
? ? [array? addObject :@"Four"];
? ? NSLog(@"array:%@",array);

----- 刪除數組中指定索引處對象 -----???
??? //-(void) removeObjectAtIndex: (unsigned) index;? ?
? ? //NSMutableArray *array = [NSMutableArray arrayWithObjects:@"One",@"Two",@"Three",nil];
? ? [array? removeObjectAtIndex :1];
? ? NSLog(@"array:%@",array);

? -----? 數組枚舉 -----??
//1、- (NSEnumerator *)objectEnumerator;? //從前向后
? ? //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;? //從后向前
? ? //NSMutableArray *array = [NSMutableArray arrayWithObjects:
? ? @"One",@"Two",@"Three",nil];
? ? NSEnumerator *enumerator;
? ? enumerator = [array reverseObjectEnumerator];

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

-----? NSValue（對任何對象進行包裝） -----
//將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);
//從Array中 提取
? ? value = [array objectAtIndex:0];
? ? [value getValue:&rect];
? ? NSLog(@"value:%@",value);

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

[objectsArray addObject:p1];
NSLog(@"p1 count:%d", [p1 retainCount]);// 輸出 2，也就是執行追加對象后，對象的計數器也被加1
//[p1 release];
//NSLog(@"p1 count:%d", [p1 retainCount]);

//同樣做數組替換時
[objectsArray replaceObjectAtIndex:0 withObject:p2];
NSLog(@"p2 count:%d", [p2 retainCount]);// 輸出 2，同樣也是2
NSLog(@"p1 count:%d", [p1 retainCount]);// 輸出 1，對象p1仍然存在
//[p2 release];
//NSLog(@"p2 count:%d", [p2 retainCount]);

//執行清空數組
[objectsArray removeAllObjects];
NSLog(@"p2 count:%d", [p2 retainCount]);// 輸出 1，對象p2仍然存在
//[p2 release];

由此可知，每次執行上面的數組操作后，要執行對象release，如上面注釋中的語句，才能保證內存不泄露。

NSSet
Unordered collection of objects.
Immutable. You cannot add or remove objects to it once it’s created.
Important methods:
+ set WithObjects :(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, ..... 一系列鍵值對。

key（鍵）在整個dictionary是唯一的，通過key可以查詢其對應的一個或多個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;

?----- 創建字典 ?-----
??? //- (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;

?----- 創建可變字典 ?-----???
//創建
? ? 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);
//刪除指定的字典
? ? [dictionary removeObjectForKey:@"3"];
? ? NSLog(@"dictionary:%@",dictionary);