(三) [OC高效系列]多用字面量语法，少用与之等价的方法

1.更加简洁

比如用方法定义一个NSNumber

    NSNumber *number = [NSNumber numberWithInt:1];
    NSNumber *number2 = @1;

2.更加清晰

比如定义一个NSDictionary

NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@"liu",@"firstName",@"yuxiao",@"lastName",nil];
    NSDictionary *dic2 = @{@"firstName":@"liu",@"lastName":@"yuxiao"};

3.更加安全

    //你或许会以为这个array的长度为4，但实际为2
    NSArray *array = [NSArray arrayWithObjects:@"你好",@"aaa",nil,@"haha",nil];
    // NSArray *array2 = @[@"你好",@"aaa",nil,@"haha"]; 直接报错

4.通过字面量+muticopy的方式创建可变数组和可变字典

NSMutableArray *array3 = [@[@1,@2,@3] mutableCopy];
    NSMutableDictionary *dic3 = [@{@"firstName":@"liu",@"lastName":@"yuxiao"} mutableCopy];