NSArray与NSDictionary使用

A，NSArray只存储Objective-C对象，而不能存储C语言中的基本数据类型，构造NSArray的时候需要记着以nil标示结尾。

NSMutableArray创建的是动态数组，可以随意添加删除元素，而NSArray一经创建不能添加删除。

#import 


void print(NSArray *arr)
{
	NSEnumerator *enu = [arr objectEnumerator];
	id obj;
	
	while (obj = [enu nextObject]) {
		printf("%s\n", [[obj description] UTF8String]);
	}
}

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	
	//静态数组
	NSArray *arr = [[NSArray alloc] initWithObjects:@"a",@"b",@"c",nil];
	printf("static array---------\n");
	print(arr);
	
	//动态数组
	NSMutableArray *marr = [[NSMutableArray alloc] init];
	[marr addObject:@"one"];
	[marr addObject:@"two"];
	[marr addObjectsFromArray:arr];
	[marr addObject:@"three"];
	[marr addObject:@"three"];
	[marr removeObjectAtIndex:(NSUInteger)2];
	[marr removeObject: @"three"];
    printf("mutable array---------\n");
	print(marr);
	
	//排序
	[marr sortUsingSelector:@selector(caseInsensitiveCompare:)];
	printf("sorted mutable array----------\n");
	print(marr);
	
	[arr release];
	[marr release];
	
	[pool drain];
    return 0;
}

运行结果如下：

static array---------
a
b
c
mutable array---------
one
two
b
c
sorted mutable array----------
b
c
one
two

总结：我们可以用Obj，Obj，Obj，... ，nil的方式来初始化一个NS数组，针对排序可以选择自定义的selector实现，而print函数中的NSEnumerator（类似迭代器）可以用来遍历数组。

B，NSDictionary字典类型与NSMutableDictionary动态字典类型

#import 

void print(NSDictionary *dic)
{
	NSEnumerator *enu = [dic keyEnumerator];
	id key;
	
	while (key = [enu nextObject]) {
		printf("%s ＝> %s\n", 
			   [[key description] UTF8String],
			   [[[dic objectForKey:key] description] UTF8String]);
	}
}

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	
	//静态字典
	NSDictionary *dic = [[NSDictionary alloc] initWithObjectsAndKeys:
						 @"one",[NSNumber numberWithInt:1],
						 @"two",[NSNumber numberWithInt:2],
						 @"three",[NSNumber numberWithInt:3],
						 nil];
	printf("static dictionary--------\n");
	print(dic);
	
	//动态字典
	NSMutableDictionary *mdic = [[NSMutableDictionary alloc] init];
	[mdic setObject:@"http://blog.csdn.net/ciaos" forKey:@"ciaos"];
	[mdic setObject:@"http://weibo.com/littley" forKey:@"penjin"];
	[mdic addEntriesFromDictionary:dic];
	[mdic setObject:@"http://localhost" forKey:@"unknown"];
	
	[mdic removeObjectForKey:@"unknown"];
	
	printf("mutable dictionary---------\n");
	print(mdic);
	
	[dic release];
	[mdic release];
	[pool drain];
    return 0;
}

运行结果如下，可以看出显示结果和插入顺序没有关系，这和C#中的字典类型一样。

static dictionary--------
3 ＝> three
1 ＝> one
2 ＝> two
mutable dictionary---------
penjin ＝> http://weibo.com/littley
3 ＝> three
ciaos ＝> http://blog.csdn.net/ciaos
2 ＝> two
1 ＝> one