第七天 IOS NSArray

定义一个数组：NSArray *array=@[@"one",@"two",@"threee",@"four"]；

数组的初始化

NSObject *obj1=[[NSObject alloc]init];

NSObject *obj2=[[NSObject alloc]init]

NSArray *array2=@[obj1,obj2];

静态初始化数组

NSArray *array3=[NSArray arrayWithObjects:@"one",@"two",@"trhee",nil];

NsArray *array4=[NSArray arrayWithObjects:obj1,obj2,nil];

获取数组的大小

NSInteger count=array4.count;

获取某个索引位置的元素

NSString *item=[array objectAtIndex:2];

数组的遍历

for(int i=0;i<count;i++)

{

NSString *item=[array objectAtIndex:i];

NSLog(@"%@",item);

}

增强形for循环

for(NSString *item in array)

{

NSString *item=[array objectAtIndex:i];

NSLog(@"%@",item);

}

获取元素的索引位置

NSUinteger index=[array indexOfObject:@"one"];

NSLog(@"%lu",index);

对象转换成字符串

NSArray *array@[c1,c2,c3];

NSString *str=[array componentsJoinedByString:@":"];

NSLog(@"%@",str);

将一个数添加到另外一个数组中

NSArray *array1=@[@"1",@"2",@"3'];

NSArray *array2=@[@"a",@"b",@"c"];

NSArray *temp=[array1 arrayByAddingObjectsFormArray:array2];

NSLog(@"%@",temp);

判断某个数组是否包含某个对象

BOOL r=[array1 containsObject :@"3"]

NSLog(@"%@",r);

枚举迭代

顺序

NSArray *array1=@[@"1",@"2",@"3"];

NSEnumerator *e=[array1 objectEnumerator];

NSString *s;

while((s=nextObject)!=nil)

{

NSLog(@"%@",s);

}

逆序

NSArray *array1=@[@"1",@"2",@"3"];

NSEnumerator *e=[array1 reverseObjectEnumerator];

NSString *s;

while((s=nextObject)!=nil)

{

NSLog(@"%@",s);

}

将数组写入到文件中

NSArray *array1=@[@"1",@"2",@"3"];

NSString *path=@"/temp/test.txt";

BOOL r=[array1 writeToFile:path atomically:YES];

NSLog("%d",r);