NSObject 属性的奇怪行为
我有一个 NSObject,用于存储/保存对象的属性,其中之一是转换为 NSString 的“Name”属性。我还使用以下命令从 SQLite DB 中提取该对象的数据:
- (void) getDataToDisplay:(NSString *)dbPath {
if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) {
NSString *queryOnStyle = [NSString stringWithFormat:
@"SELECT WineId, Name FROM wine WHERE StyleId = %d", dataManager.styleId];
const char *sql = [queryOnStyle UTF8String];
sqlite3_stmt *selectstmt;
if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {
while(sqlite3_step(selectstmt) == SQLITE_ROW) {
Wine *w = [[Wine alloc] init];
w.wineId = sqlite3_column_int(selectstmt, 0);
w.wineName = [NSString stringWithUTF8String:
(char *)sqlite3_column_text(selectstmt, 1)];
[dataManager.wines addObject:w];
[w release];
}
}
}
else
sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
}
Wine 是我的对象。如果我此时记录 w.wineName
,就没有问题。当我尝试从自定义 tableView 中的数组 dataManager.wines
中访问对象的属性时,稍后会出现问题。它突然将我的 wineName
视为 UIImageView
而不是 NSString
...
我一生都无法追溯到任何被投射的东西作为一个 UIImageView ,并且不知道为什么它会这样设置该属性。这是我的自定义 tableView 的代码:
#pragma mark -
#pragma mark HorizontalTableViewDelegate methods
- (NSInteger)numberOfColumnsForTableView:(HorizontalTableView *)tableView {
return [dataManager.wines count];
}
- (UIView *)tableView:(HorizontalTableView *)aTableView viewForIndex:(NSInteger)index {
UIView *vw = [aTableView dequeueColumnView];
if (!vw) {
[[NSBundle mainBundle] loadNibNamed:@"ColumnView" owner:self options:nil];
vw = self.columnView;
self.columnView = nil;
}
// Get the wineId from the array of wineId integers
Wine *w = [dataManager.wines objectAtIndex:index];
int tempWineId = w.wineId;
NSString *tempWineName = [NSString stringWithFormat:@"%@", w.wineName];
NSLog(@"%@", tempWineName); \\RETURNS TEMPWINENAME AS A UIIMAGEVIEW
[w release];
return vw;
}
- (CGFloat)columnWidthForTableView:(HorizontalTableView *)tableView {
//TODO: This value needs to change if changed in IB
return 209.0f;
}
有什么想法吗?
I have an NSObject
that I am using to store/hold properties of an object, one of them being a "Name" property cast as an NSString
. I am also pulling data from a SQLite DB for said object using the following:
- (void) getDataToDisplay:(NSString *)dbPath {
if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) {
NSString *queryOnStyle = [NSString stringWithFormat:
@"SELECT WineId, Name FROM wine WHERE StyleId = %d", dataManager.styleId];
const char *sql = [queryOnStyle UTF8String];
sqlite3_stmt *selectstmt;
if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {
while(sqlite3_step(selectstmt) == SQLITE_ROW) {
Wine *w = [[Wine alloc] init];
w.wineId = sqlite3_column_int(selectstmt, 0);
w.wineName = [NSString stringWithUTF8String:
(char *)sqlite3_column_text(selectstmt, 1)];
[dataManager.wines addObject:w];
[w release];
}
}
}
else
sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
}
Wine being my object. If I were to log w.wineName
at this point, there is no problem. The problem occurs later when I try to access the properties of the object from within the array, dataManager.wines
, in a custom tableView. It suddenly treats my wineName
as a UIImageView
rather than an NSString
...
I for the life of me cannot trace anything back to ever being cast as a UIImageView
and have no idea why it would be setting just that property as such. Here is the code for my custom tableView:
#pragma mark -
#pragma mark HorizontalTableViewDelegate methods
- (NSInteger)numberOfColumnsForTableView:(HorizontalTableView *)tableView {
return [dataManager.wines count];
}
- (UIView *)tableView:(HorizontalTableView *)aTableView viewForIndex:(NSInteger)index {
UIView *vw = [aTableView dequeueColumnView];
if (!vw) {
[[NSBundle mainBundle] loadNibNamed:@"ColumnView" owner:self options:nil];
vw = self.columnView;
self.columnView = nil;
}
// Get the wineId from the array of wineId integers
Wine *w = [dataManager.wines objectAtIndex:index];
int tempWineId = w.wineId;
NSString *tempWineName = [NSString stringWithFormat:@"%@", w.wineName];
NSLog(@"%@", tempWineName); \\RETURNS TEMPWINENAME AS A UIIMAGEVIEW
[w release];
return vw;
}
- (CGFloat)columnWidthForTableView:(HorizontalTableView *)tableView {
//TODO: This value needs to change if changed in IB
return 209.0f;
}
any ideas?
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在 RichB 的问题评论中解决:
w.wineName
是一个保留的属性吗?这听起来有点像弦被自动释放。您能发布Wine
对象的定义吗?Resolved in comments of question by RichB:
is
w.wineName
a retain'ed property ? This sounds a bit like the string is being auto released. Could you post the definition of theWine
object?