'=='的左操作數是垃圾值

Question

當我分析我的ios項目時，我收到此錯誤

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

這就是代碼出現的地方。這個方法用於對從DB返回給我的數組進行排序。

- (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

編譯器抱怨是因為它認為在result有值之前可以達到==比較。

給出代碼的最佳選擇是使用else if 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.
}
...

或者你可以這樣做：

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];
...

甚至這個：

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

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

這樣編譯器就知道如果達到比較，則result的值已經設置好了。

Answer 2

我認為只是llvm“求解器”不理解<，>或==中的一個必須與manufacturerID [12]比較相關才是真的。 嘗試刪除if (manufacturerID1 == manufacturerID2)塊，以便它可以告知未使用未初始化的result值。 盡管你的評論，你實際上並沒有初始化它的價值。