测试:数组拼接

//    NSArray * arr = @[@"1",@"2",@"3",@"4"];

//    NSArray * arr1 = @[@"5",@"6",@"7"];

//  NSArray * arr3 =  [arr arrayByAddingObjectsFromArray:arr1];

//    NSLog(@"%@",arr3);

//    NSMutableArray * arr = [[NSMutableArray alloc]initWithArray:@[@"1",@"2",@"3",@"4"]];

//    NSArray * arr1 = @[@"5",@"6",@"7"];

//    [arr addObjectsFromArray:arr1];