objective-c 错题

    //1,

    NSString *name = [[NSString alloc]initWithString:@"张三"];

    NSLog(@"%d",[name retainCount]);

    //2014-11-27 20:43:20.290 OC考试错题[1750:303] -1

    

    //2,

    NSString* testObject = [[NSData alloc] init];

    //编译时，NSString类型，运行时，NSData类型

    

    //3,

    NSArray *(^aBlock)(NSString * str,NSString *str2);

    //声明一个返回值为NSArray，并且带两个字符串对象的BLOCK类型变量

    

    //4,

    NSMutableDictionary * dic = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"1",@"2",@"2",@"3",@"3",@"4", nil];

    NSArray *arr = [[NSArray alloc] initWithArray:[dic allKeys]];

    NSString *str = [[NSString alloc] initWithFormat:[arr objectAtIndex:0],[arr objectAtIndex:1],[arr objectAtIndex:2]];

    NSLog(@"%@",str);

    //2014-11-27 20:47:22.678 OC考试错题[1761:303] 2

    

    //5,

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    NSString *sstr = [NSString stringWithFormat:@"abc"];

    NSString *str2 = [sstr retain];

    [pool release];

    NSLog(@"sstr retainCount = %ld,str2 retainCount = %ld",[sstr retainCount],[str2 retainCount]);

    // sstr retainCount = 1,str2 retainCount = 1

    

    

    //6,

    NSMutableDictionary * dic1 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"1",@"2",@"1",@"3",@"1",@"4", nil];

    NSArray *arr1 = [[NSArray alloc] initWithArray:[dic1 allKeys]];

    NSArray *arr2 = [[NSArray alloc] initWithArray:[dic1 allValues]];

    NSMutableDictionary *dic2 = [[NSMutableDictionary alloc] initWithObjects:arr1 forKeys:arr2];

    NSLog(@"%@",dic2);

    //  1 = 4;

    

    //7,将@”2B青年”替换成@”文艺青年”

    NSRange range1 = {0,2};

    [@"2B青年" stringByReplacingCharactersInRange:range1 withString:@"文艺"];

    

    //8,

    NSMutableDictionary * dic3 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"1",@"2",@"2",@"3",@"3",@"4", nil];

    [dic3 setObject:@"1" forKey:@"3"];

    [dic3 removeObjectForKey:@"1"];

    NSLog(@"%@",dic3);

    //  2 = 1;3 = 1;4 = 3;

    

    //9,在类方法中bu可以使用实例变量。

    

    //10,实例对象都是通过调用类方法生成的。

    

    

    

    

    

    return 0;