Question

我在分析我的ios项目时遇到此错误

The left operand of '==' is a garbage value

这就是代码出现的位置。此方法用于对从DB返回给我的数组进行排序。

- (NSMutableArray *)startSortingTheArray:(NSMutableArray *)unsortedArray
{
    [unsortedArray sortUsingComparator:^ NSComparisonResult(SearchResultItem *d1, SearchResultItem *d2) {
        //initalize comparison
        NSComparisonResult result;

        NSInteger manufacturerID1 = d1.manufacturerID;
        NSInteger manufacturerID2 = d2.manufacturerID;
            if (manufacturerID1 > manufacturerID2)
                return NSOrderedAscending;
            if (manufacturerID1 < manufacturerID2)
                return NSOrderedDescending;
            if (manufacturerID1 == manufacturerID2) {

            NSString *model1 = d1.model;
            NSString *model2 = d2.model;
            result = [model1 localizedCompare:model2];
        }
        if (result == NSOrderedSame) {
//..

Answer 1

编译器抱怨，因为它认为在==有值之前可以进行result比较。

代码的最佳选择是使用else if和else：

if (manufacturerID1 > manufacturerID2)
    return NSOrderedAscending; // we won't reach the comparison so result doesn't matter
else if (manufacturerID1 < manufacturerID2)
    return NSOrderedDescending; // we won't reach the comparison so result doesn't matter
else {
    NSString *model1 = d1.model;
    NSString *model2 = d2.model;
    result = [model1 localizedCompare:model2]; // in any other case, result will be set.
}
...

或者你可以这样做：

NSComparisonResult result;
...
if (manufacturerID1 > manufacturerID2)
    return NSOrderedAscending;
else if (manufacturerID1 < manufacturerID2)
    return NSOrderedDescending;

NSString *model1 = d1.model;
NSString *model2 = d2.model;
result = [model1 localizedCompare:model2];
...

甚至这个：

if (manufacturerID1 > manufacturerID2)
    return NSOrderedAscending;
else if (manufacturerID1 < manufacturerID2)
    return NSOrderedDescending;

NSComparisonResult result = [d1.model localizedCompare:d2.model];
...

这样编译器知道如果达到比较，则result的值已经设置。

Answer 2

我认为只是llvm“求解器”才能理解，对于manufacturerID [12]比较而言，＆lt;，＆gt;或==中的一个必须是真的。尝试删除if (manufacturerID1 == manufacturerID2)块，以便它可以告知未使用未初始化的result的值。尽管你的评论，你实际上并没有初始化它的价值。

'=='的左操作数是垃圾值

2 个答案: