//1.创建一个可变数组

NSMutableArray *mArray = [NSMutableArray arrayWithObjects:@"a",@"b",@"a",@"b",@"a",@"b",@"a",@"b",nil];

NSMutableArray *A = [NSMutableArray array];

NSMutableArray *B = [NSMutableArray array];

for(int i =0; i < mArray.count; i++) {

if(i  % 2 == 0) {

[A addObject:mArray[i]];

}else{

[B addObject:mArray[i]];

}

}

XPFLog(@"双数%@单数%@", A, B);

打印结果：

双数(

a,

a,

a,

a

)

单数(

b,

b,

b,

b

)