//数组的方法调用与熟练    NSArray *array=@[@11,@22,@33,@"ldq"];    NSArray *array1 =[array arrayByAddingObject:@"dkf"];    array1=[NSArray arrayWithObjects:@11,@222, nil];    //NSLog(@"%@",array1);        NSArray *array3=[NSArray arrayWithArray:array];    //[array3 ];    //NSLog(@"%@",array3);    NSString *array11[]={@"123",@"344"};    NSArray *array4=[[NSArray alloc]initWithObjects:array11 count:2];    //NSLog(@"###%@",array4);    [array4 writeToFile:@"/Users/apple/Desktop/test.plist" atomically:YES];    NSArray *ary= [[NSArray alloc]initWithContentsOfFile:@"/Users/apple/Desktop/test.plist"];        NSLog(@"$$%@",ary);    NSInteger cout=[ary count];    NSLog(@"@@@%d",cout);        NSInteger a=[ary indexOfObject:@"344"];    NSLog(@"%d",a);    NSMutableArray *mArray = [NSMutableArray arrayWithCapacity:10];    [mArray addObjectsFromArray:ary];    [mArray replaceObjectAtIndex:1 withObject:@"www"];    NSLog(@"%@",mArray);        //排序数组，用自己写的方法comper:    Student *stu1=[[Student alloc]init];    stu1.age=56;    Student *stu2=[[Student alloc]init];    stu2.age=45;    Student *stu3=[[Student alloc]init];    stu3.age=78;    NSArray *a1=[NSArray arrayWithObjects:stu1,stu2,stu3, nil];    NSArray *a2=[a1 sortedArrayUsingSelector:@selector(comper:)];    for (Student *st in a2) {        NSLog(@"%d",st.age);    }            return YES;