ios - NSRange 奇怪的行为

Question

我的设备 (iPhone iOS 4.3) 上有奇怪的 NSRange 行为。此代码在设备和模拟器上有不同的行为。

for (Location *location in locationArray)
{
    NSRange range1 = [location.name rangeOfString:searchText options:NSCaseInsensitiveSearch];
    NSRange range2 = [location.streetAddress rangeOfString:searchText options:NSCaseInsensitiveSearch];
    NSRange range3 = [location.postalCode rangeOfString:searchText options:NSCaseInsensitiveSearch];

if (range.length1 > 0 | range2.length > 0 | range3.length > 0)
    [self.filteredList addObject:location];
}

如果某些属性的值范围为 nil。该属性的长度在设备上等于 2，在模拟器中等于零。

我做错了什么吗？

Answer 1

The Objective-C Programming Language

The value returned from a message to nil may also be valid:

• If the method returns an object, then a message sent to nil returns 0 (nil). For example: Person *motherInLaw = [[aPerson spouse] mother]; If the spouse object here is nil, then mother is sent to nil and the method returns nil.
• If the method returns any pointer type, any integer scalar of size less than or equal to sizeof(void*), a float, a double, a long double, or a long long, then a message sent to nil returns 0.
• If the method returns a struct, as defined by the Mac OS X ABI Function Call Guide to be returned in registers, then a message sent to nil returns 0.0 for every field in the struct. Other struct data types will not be filled with zeros.
• If the method returns anything other than the aforementioned value types, the return value of a message sent to nil is undefined.

它适用于 Mac OS X，但我认为可以肯定地说，如果消息目标为 nil，您不应该依赖返回的结构值。