NSNumber:stringValue崩溃,描述有效

Question

[measureValue stringValue] 给了我这个例外:

由于未捕获的异常'NSInvalidArgumentException'而终止应用程序,原因:' - [NSCFString stringValue]:无法识别的选择器发送到实例0x4dde570'

[measureValue description] 工作得很好

但我想我应该stringValue在代码中使用,对吧？

这是代码:

NSNumber *measureValue = [NSString stringWithFormat:@"%i", [cellContent integerValue]];

//if imperial (inches)
if ([[[NSUserDefaults standardUserDefaults] stringForKey:@"Measure"] isEqualToString:@"Imperial"] ) {

    //if height
    if ([currentQuestion isEqualToString:@"Height"]) {
        measureValue = [NSNumber numberWithDouble:(2.54 * [measureValue doubleValue])];
    //elseif weight
    } else {
        measureValue = [NSNumber numberWithDouble:(0.45359237 * [measureValue doubleValue])];
    }

    //NSLog(@"%@", [measureValue stringValue]);
    cellContent = [measureValue description];

Answer 1

 NSNumber *measureValue = [NSString stringWithFormat:@"%i", [cellContent integerValue]];

该行返回NSString,而不是NSNumber.您正在将stringValue发送到NSString.