无法解决错误“[__NSCFBoolean length]: unrecognized selector sent to instance" [英] Unable to solve the error "[__NSCFBoolean length]: unrecognized selector sent to instance"

问题描述

代码

NSDictionary *dict = [self.catArray objectAtIndex:indexPath.row];
NSURL *U1 =[NSURL URLWithString:[dict objectForKey:@"img"]];

[DownloadManager downloadImageWithURL:[NSURL URLWithString:[dict objectForKey:@"img"]] completionBlock:^(BOOL succeeded, UIImage *image) {
    if (succeeded) {

        [cell.iconImgView setImage:image];

    }
}];

出现错误

[__NSCFBoolean length]:无法识别的选择器发送到实例

[__NSCFBoolean length]: unrecognized selector sent to instance

推荐答案

您的问题与此行有关:

NSURL *U1 =[NSURL URLWithString:[dict objectForKey:@"img"]];

问题是由您假设的事实引起的:

The problem is caused by the fact that you assume:

[dict objectForKey:@"img"]

返回一个 NSString 而实际上它返回一个表示布尔值的 NSNumber.

is returning an NSString when in fact it is returning an NSNumber representing a boolean value.

您需要弄清楚为什么字典中的数据不正确，或者您需要使用正确的密钥来获取 URL.

You need to either figure out why the data in the dictionary is incorrect or you need to use the correct key to get the URL.

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