隱式轉換錯誤NSIndexPath

Question

我有這種相對簡單的helper方法：

- (float)imageHeightForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    CGRect screenRect = [[UIScreen mainScreen] bounds]; 
    CGFloat screenWidth = screenRect.size.width; 
    float imageWidth = [[self.widthArray objectAtIndex:indexPath.row] floatValue]; 
    float ratio = screenWidth/imageWidth; 
    float imageHeight = ratio * [[self.heightArray objectAtIndex:indexPath.row] floatValue]; 
    return imageHeight; 
} 

的另一種方法，但這種方法調用的時候，其工作完全正常：

- (UIImage *)imageWithImage:(UIImage *)image forRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    CGRect screenRect = [[UIScreen mainScreen] bounds]; 
    CGFloat newWidth = screenRect.size.width; 
    CGFloat newHeight = [self imageHeightForRowAtIndexPath:indexPath.row]; 
    UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight)); 
    [image drawInRect:CGRectMake(0, 0, newWidth, newHeight)]; 
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
    return newImage; 
} 

編譯器說： Implicit conversion from 'NSInteger' to 'NSIndexPath' is disallowed

我不知道爲什麼以及如何解決這個問題。任何想法？

Answer 1

你有2種方法：

1. - (float)imageHeightForRowAtIndexPath:(NSIndexPath *)indexPath
2. - (UIImage *)imageWithImage:(UIImage *)image forRowAtIndexPath:(NSIndexPath *)indexPath

每一個有NSIndexPath *參數。

現在，imageWithImage:forRowAtIndexPath:您呼叫imageHeightForRowAtIndexPath:：

[self imageHeightForRowAtIndexPath:indexPath.row] 

，並在該行正在從indexPath（一NSInteger）服用row，並試圖將它傳遞給imageHeightForRowAtIndexPath:：，這是預期的NSIndexPath * 。

這是錯誤的原因，因爲編譯器知道期望NSIndexPath *，它知道你提供的是NSInteger。

來解決，該代碼更改爲：

CGFloat newHeight = [self imageHeightForRowAtIndexPath:indexPath];