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;