iOS Collection 集合

1、NSNumber

    // NSNumber numberWithChar    NSNumber * num1 = [NSNumber numberWithChar:'A'];    NSLog(@"num1=%@",num1);    // numberWithInt    // numberWithFloat    // numberWithBool    num1 = [NSNumber numberWithBool:NO];    NSLog(@"num1=%@",num1);    // charVaule    // intValue    // floatValue    // boolValue    NSLog(@"%hhd",[num1 boolValue]);

上面Demo的Log输出为:

2015-06-22 09:49:37.591 ObjC03[5534:303] num1=65
2015-06-22 09:49:37.595 ObjC03[5534:303] num1=0
2015-06-22 09:49:37.596 ObjC03[5534:303] 0

2、NSValue

    // NSValue    CGSize si;    si.height = 20;    si.width = 10;    // char a[2] = {'a','b'};    NSValue * value = [NSValue valueWithBytes:&si objCType:@encode(CGSize)];    // valueWithPoint    // valueWithSize    // valueWithRect    CGSize size =[value sizeValue];    NSLog(@"width=%f,height=%f",size.width,size.height);

上面代码的Log输出为：

2015-06-22 09:49:37.596 ObjC03[5534:303] width=10.000000,height=20.000000

3、Collection集合

Collection(集合)是能够容纳多个事物的容器，在iOS中的集合有数组，字典，集合；

数组: 可以包含相同的元素

• NSArray：不可变数组，可以存放多个对象，实例化的时候以nil表示结束，通过下标索引对象，NSArray中无法添加，删除，修改元素；
• NSMutableArray：可变数组，是NSArray的子类，相比NSArray增加了添加，删除，修改元素的功能；

字典:

• NSDictionary：不可变字典，存放多个键值对(key-value)，最后以nil结束，字典中的对象存储没有顺序，只能使用key来索引每个对象，不可以添加，删除，修改元素；
• NSMutableDictionary：可变字典，是NSDirctionary的子类；

在实例化不可变字典对象时，如果在参数的前边已经包含了某一个关键字key，那么在后边出现的相同的关键字则不会添加到字典内；

在对可变字典对象添加元素时，如果在字典对象内已经包含了对应的key，则会用新的value值替换之前的value值；

集合: 不能包含相同的元素

• NSSet：不可变集合，可以存放多个对象，以nil表示结束，对象在set中是无序的，不可以添加，删除，修改元素；
• NSMutableSet：可变集合，是NSSet的子类；

可变类通常比不可变类多了增删改的功能；

Set集合是无序的，随机取数据；

Collection的内存管理：

Collection会对自己内部的元素负责，元素添加(含初始化)到Collection的时候，元素会自动retain，当元素remove的时候，元素会自动release，当Collection释放销毁的时候，会先让内部元素release，然后自己再release；

4、NSArray和NSMutableArray

NSMutableArray是NSArray的子类，NSArray长度固定，而NSMutableArray长度可变；

    // NSArray    NSArray *arr = [[NSArray alloc] initWithObjects: @"zero", @"one", nil];    // count    NSLog(@"arr.count=%lu",[arr count]);    // objectAtIndex    NSLog(@"arr at 1 = %@",[arr objectAtIndex:1]);    NSString *str = [NSString stringWithFormat:@"ten"];    // [arr insertValue:<#(id)#> inPropertyWithKey:<#(NSString *)#>];        // NSMutableArray    NSMutableArray *arr1 = [[NSMutableArray alloc]initWithCapacity:12];    // arr1 = [NSMutableArray arrayWithCapacity:12];    // addObject    [arr1 addObject:@"two"];    NSLog(@"arr1.count=%lu",[arr1 count]);    NSLog(@"arr1 at 0 = %@",[arr1 objectAtIndex:0]);    [arr1 addObject:str];    NSLog(@"arr1.count=%lu",[arr1 count]);    NSLog(@"arr1 at 1 = %@",[arr1 objectAtIndex:1]);    // removeAllObjects    // removeLastObject    // removeObjectAtIndex    // replaceObjectAtIndex    [arr1 replaceObjectAtIndex:1 withObject:@"three"];    NSLog(@"arr1 at 1 = %@",[arr1 objectAtIndex:1]);

上面代码的Log输出为：

2015-06-22 09:49:37.597 ObjC03[5534:303] arr.count=2
2015-06-22 09:49:37.598 ObjC03[5534:303] arr at 1 = one
2015-06-22 09:49:37.599 ObjC03[5534:303] arr1.count=1
2015-06-22 09:49:37.603 ObjC03[5534:303] arr1 at 0 = two
2015-06-22 09:49:37.605 ObjC03[5534:303] arr1.count=2
2015-06-22 09:49:37.612 ObjC03[5534:303] arr1 at 1 = ten
2015-06-22 09:49:37.613 ObjC03[5534:303] arr1 at 1 = three

5、NSDictionary和NSMutableDictionary

字典中 key 一般用 NSString 或者 NSNumber，而且值可以是任一类型；

值对象不能为nil；

    // NSDictionary    // -(id)initWithObjects :(NSArray *) objectforKeys: (NSArray *)keys    // +(id)dictionaryWithObject :id(anObject)    // [NSDictionary dictionaryWithObject:<#(id)#> forKey:<#(id<NSCopying>)#>];    NSDictionary * dic = [[NSDictionary alloc] initWithObjectsAndKeys:@"value1",@"key1",@"value2",@"key2", nil];    // count    NSLog(@"dic.count = %lu",[dic count]);    // get allKeys    NSArray *arrKeys =[dic allKeys];    int count = (int)[arrKeys count];        // loop1    for(int i = 0;i<count ;i++){        NSLog(@"dic.key%d = %@",(i + 1),[arrKeys objectAtIndex:i]);        // 1.getValue from key        NSLog(@"dic.value = %@",[dic objectForKey:[arrKeys objectAtIndex:i]]);        // 2.getValue from key        // NSLog(@"dic.value = %@",[dic valueForKey:[arrKeys objectAtIndex:i]]);    }    // loop2    NSString * key;    for(k in dic){        NSLog(@"key = %@ , value=%@", key , [dic valueForKey:key]);    }        // NSMutableDictionary    NSMutableDictionary *dic2 = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"v1",@"k1",@"v2",@"k2", nil];    [dic2 setObject:@"v3" forKey:@"k3"];    NSLog(@"dic2.length = %d",(int)[dic2 count]);    NSLog(@"dic2's value of k3 = %@",[dic2 objectForKey:@"k3"]);    // setValue    [dic2 setValue:@"k3_new" forKey:@"k3"];    NSLog(@"dic2's value of k3 = %@",[dic2 objectForKey:@"k3"]);    // removeObjectForKey :(id)key;    // removeAllObjects;

上面代码的输出为:

2015-06-22 09:59:53.624 ObjC04[5574:303] dic.count = 2
2015-06-22 09:59:53.628 ObjC04[5574:303] dic.key1 = key1
2015-06-22 09:59:53.629 ObjC04[5574:303] dic.value = value1
2015-06-22 09:59:53.630 ObjC04[5574:303] dic.key2 = key2
2015-06-22 09:59:53.632 ObjC04[5574:303] dic.value = value2
2015-06-22 09:59:53.634 ObjC04[5574:303] key = key1 , value=value1
2015-06-22 09:59:53.635 ObjC04[5574:303] key = key2 , value=value2
2015-06-22 09:59:53.636 ObjC04[5574:303] dic2.length = 3
2015-06-22 09:59:53.637 ObjC04[5574:303] dic2's value of k3 = v3
2015-06-22 09:59:53.638 ObjC04[5574:303] dic2's value of k3 = k3_new

6、NSSet和NSMutableSet

NSSet 集合和数组差不多，不过集合中不能存放相同的对象，是一组单值对象的集合，并且被存放到集中的元素是无序的；

    // NSSet    NSSet * set = [NSSet setWithObjects:@"zero", @"one", @"three", nil];    // -(id)initWithObjects    NSLog(@"set's count = %d",(int)[set count]);    // allObjects    count = (int)[set count];    NSArray *objs = [set allObjects];    // loop1    for(int i = 0;i<count ;i++){        NSLog(@"%@",[objs objectAtIndex:i]);    }    // loop2    for(NSString * e in objs){        NSLog(@"e = %@",e);    }        // anyObject    NSString * obj = [set anyObject];    NSLog(@"anyObject=%@",obj);    // isEqualToSet : compare two set    // member : obj (contains)    NSLog(@"is contains 'one' =%@",[set member:@"one"]);    NSLog(@"is contains 'two' =%@",[set member:@"two"]);        // NSMutableSet    // 指定新分配的集合为size个成员存储空间    NSMutableSet * set1 = [[NSMutableSet alloc] initWithCapacity:12];    [set1 addObject:@"zero_0"];    NSString * any1 = [set1 anyObject];    NSLog(@"any1 = %@",any1);

以上代码的Log输了为：

2015-06-22 09:59:53.639 ObjC04[5574:303] set's count = 3
2015-06-22 09:59:53.641 ObjC04[5574:303] zero
2015-06-22 09:59:53.642 ObjC04[5574:303] one
2015-06-22 09:59:53.643 ObjC04[5574:303] three
2015-06-22 09:59:53.643 ObjC04[5574:303] e = zero
2015-06-22 09:59:53.644 ObjC04[5574:303] e = one
2015-06-22 09:59:53.645 ObjC04[5574:303] e = three
2015-06-22 09:59:53.647 ObjC04[5574:303] anyObject=zero
2015-06-22 09:59:53.649 ObjC04[5574:303] is contains 'one' =one
2015-06-22 09:59:53.651 ObjC04[5574:303] is contains 'two' =(null)
2015-06-22 09:59:54.376 ObjC04[5574:303] any1 = zero_0

7、快速枚举

枚举：对集合中的元素依次，不重复地一一进行遍历。
传统语法中，枚举一般通过 for 循环来进行：

for(int i = 0;i < n；i++){<span style="white-space:pre"></span>id anObject = [array objectAtIndex：i];}

Objective-C 2.0 中提供了一种简洁的特色语法，令你可以安全又快速地对集合中的元素进行枚举。
for...in 是 Objective-C 2.0 中的特色语法，它的标准形式如下：

for(Type newVariable in expression){<span style="white-space:pre"></span>statements;}

或者：

Type variable;for(variable in expression){<span style="white-space:pre"></span>statements;}

遍历：

    [dic enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {        NSLog(@"%@=%@,end = %d",key, obj, *stop);    }];        [arr enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {        NSLog(@"arr:%@ %d",obj, *stop);    }];