用PFQuery填充UIPickerView

Question

我正在嘗試使用通過PFQuery接收的列中的屬性加載uipickerview。 我認為我已經能夠成功加載這些項目，並使用findObjectsInBackgroundWithBlock方法將其存儲在viewDidLoad方法的數組中。 登錄到控制台后，數組（查詢結果，現在存儲在_locationArray中）如下所示：

     "<Cinema:TWdBNfe6QF:(null)> {\n    Location = NY;\n    Name = A;\n}",
    "<Cinema:uCXICOaQFw:(null)> {\n    Location = DC;\n    Name = B;\n}",
    "<Cinema:TQ1F0Bj5OS:(null)> {\n    Location = LA;\n    Name = \"A, ICM\";\n}",
    "<Cinema:xiUXXYFhAl:(null)> {\n    Location = \"San Francisco\";\n    Name = C;\n}"

我想在uipickerview中顯示位置。

    - (NSInteger)pickerView:(UIPickerView *)pickerView
    numberOfRowsInComponent:(NSInteger)component
    {
    return [_locationArray count];
    NSLog(@"%lu", (unsigned long)[_locationArray count]);//It never logs this count
    }

    - (NSString *)pickerView:(UIPickerView *)pickerView
         titleForRow:(NSInteger)row
        forComponent:(NSInteger)component
    {
    // I'm not sure how to get the location attribute
    // I get a runtime error if I try to access the _locationArray[row] element 
    }

請幫忙！ 提前致謝。

Answer 1

我要做的是使用for-in循環遍歷數組，並創建要添加到的新NSMutableArray 。 例如：

在標題中：

@property NSMutableArray *stringsArray;//Make sure to init in viewDidLoad

在.m中：

for(PFObject *object in _locationArray)
{
   [self.stringsArray addObject:[object objectForKey:@"Location"]];

}

接着：

- (NSString *)pickerView:(UIPickerView *)pickerView
         titleForRow:(NSInteger)row
        forComponent:(NSInteger)component
    {
       return [self.stringsArray objectAtIndex:row];
    }