用法总结：NSArray,NSSet,NSDictionary
iphone_dev_note 2011-05-07 14:31:08 阅读67 评论0
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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
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);