数组越界
NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"1",@"2",@"3", nil];
NSLog(@"index:%@---noneDataIndex:%zd",@"1",@"4");
[arr exchangeObjectAtIndex:[arr indexOfObject:@"1"] withObjectAtIndex:[arr indexOfObject:@"4"]];
打印结果：
index:1---noneDataIndex:4402863976
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM exchangeObjectAtIndex:withObjectAtIndex:]: index 9223372036854775807 beyond bounds [0 .. 2]'
原因分析：获取数组中一个不存在的对象的index时，获取到的值是一个比较大随机数值，在使用exchangeObjectAtIndex时就会产生崩溃现象，所以要做提前做好判断。
