用法總結：NSArray,NSSet,NSDictionary
NSArray 用於對象有序集合（數組）
NSSet 用於對象無序集合 (集合)
NSDictionary用於鍵值映射（字典）
以上三種集合類是不可變的（一旦初始化后，就不能改變）
以下是對應的三種可變集合類(這三種可變集合類是對應上面三種集合類的子類)：
NSMutableArray
NSMutableSet 可修改的集合。主要用於集合運算（並集，交集，差集）
NSMutableDictionary 允許用戶添加和刪除key和value
注：這些集合類只能容納cocoa對象（NSOjbect對象），如果想保存一些原始的C數據（例如，int, float, double, BOOL等），則需要將這些原始的C數據封裝成NSNumber類型進行存儲。NSNumber對象是cocoa對象，可以被保存在集合類中。
=================== 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中的對象個數
- (id)objectAtIndex:(int)index; // 得到索引為i的對象
- (BOOL)containsObject:(id)anObject; // 當anObject出現在array中，則返回yes（實際是通過isEqual:方法來判斷）
- (unsigned)indexOfObject:(id)anObject; // 查找array中的anObject,並返回其最小索引值。沒找到返回NSNotFound.
- (void)makeObjectsPerformSelector:(SEL)aSelector;
- (NSArray *)sortedArrayUsingSelector:(SEL)aSelector;
- (id)lastObject; // 得到array中最后一個對象。如果array中沒有任何對象存在，則返回nil
注：
類方法arrayWithObjects 可以創建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];
-----創建數組 -----
//NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSArray *monthNames = [NSArray arrayWithObjects:@"January",@"February",@"March",@"April",@"May",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]);
注：初始化一個數組時，經常使用initWithObject 和 initWithObjects。沒有s的表示使用一個指針初始化NSArray，初始化后，這個NSArray的實例只有一個數據，所以在調用沒有s的函數的時候是不能以nil結束的；但是有s的就不一樣了，哪怕只有一個數據，或者沒有數據，必須使用一個nil結束。
------ 從一個數組拷貝數據到另一數組(可變數級) -------
//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];
//快速枚舉
//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];
=================== NSMutableArray ====================
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中的對象依次添加進去。
- (void)insertObject:(id)anObject atIndex:(int)index; //在索引index處插入anObject, 若index被占用，會把之后的object向后移。
- (void)removeObjectAtIndex:(int)index; //刪除index處的對象，后面的對象依次向前移。
- (void)removeObject:(id)anObject; // 刪除所有和anObject相等的對象，同樣使用isEqual:作為相等比較方法.
- (void)removeAllObjects;
注：我們不能把nil加到array中。但有時候我們真想給array加一個空的對象，可以使用NSNull來做這件事。如：
[myArray addObject:[NSNull null]];
-----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:
+ setWithObjects:(id)firstObj, ...; // nil terminated
- (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. 可修改的集合。主要用於集合運算（並集，交集，差集）
+ (NSMutableSet *)set;
- (void)removeObject:(id)anObject;
- (void)unionSet:(NSSet *)otherSet; // 求 並集
- (void)minusSet:(NSSet *)otherSet; // 求 差集
- (void)intersectSet:(NSSet *)otherSet; // 求 交集
=================== NSDictionary ====================
- (NSUInteger)hash & - (BOOL)isEqual:(NSObject *)obj
Important methods:
+ dictionaryWithObjectsAndKeys: (id)firstObject, ...;
- (id)objectForKey:(id)key; //返回和key相關聯的value。 如果沒有和key相關聯的value，則返回nil。
- (NSArray *)allKeys; // 返回一個包含所有key的array
- (NSArray *)allValues;
Enumerators 也就是 iterators 或 enumerations.我們可以使用它來一步一步迭代出集合中的所 有成員.
下面是我們可能使用它來列 舉所有的 key- ‐vaule 對
NSEnumerator *e = [myDict keyEnumerator];
for (NSString *s in e) {
NSLog(@"key is %@, value is %@", s, [myDict objectForKey:s]);
}
注：NSArray 也有一個類似的方法得到 array 的成員迭代 器 : objectEnumerator
//- (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; // 創建一個空的dictionary
- (void) removeObjectForKey:(id)key; // 從dictionary中刪除一條記錄，key以及和它對應的value
- (void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;
//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);