Question

我正在尝试创建我的计算的一个plist但事实证明列表是空的....请帮助这里是我的code.is有任何其他方法将字符串写入除此之外的文件... < / p>

-(float)calculate
{
    if(!self.operatorLabel.text.length)
        return self.operand2;
    float result=0;
    switch([self.operatorLabel.text characterAtIndex:0])
    {
        case '+':result=self.self.operand1+self.operand2;
            break;
        case '-':result=self.operand1-self.operand2;
            break;
        case '*':result=self.operand1*self.operand2;
            break;
        case '/':if(self.operand2==0)
            divideByZeroFlag=true;
        else
            result=self.operand1/self.operand2;
            break;
        default:self.operand1=0;
            result=self.operand2;
            break;
    }
    if(!divideByZeroFlag&&self.operand1!=0)
    {

        NSString *data=[NSString stringWithFormat:@"%g%@%g=%g",self.operand1,self.operatorLabel.text,self.operand2,result];
        NSMutableDictionary *dat;
        [dat setObject:data forKey:@"nthing"];
        [dat writeToFile:@"memory.plist" atomically:YES];
    }
    return result;
}

Answer 1

1 - 您必须初始化dat。

2 - [NSDictionary writeToFile]期望完整路径，而不仅仅是名称。

修改

要创建路径，请执行以下操作：

+ (NSString*) createFullFilePath:(NSString *)fileName { //Look at documents for existing file NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *path = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@", fileName]]; NSFileManager* fileManager = [NSFileManager defaultManager]; if(![fileManager fileExistsAtPath:path]) { NSError *error; [fileManager createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:&error]; if (error) NSLog (@"%@", [error localizedDescription]); } return path; }

完成后，使用以下代码写入该路径（请注意，这也会初始化字典（检查NSLogs以查看您正在执行的操作会产生结果）：

NSString * path = [self createFullFilePath:@"memory.plist"]; NSLog (@"@%", path); NSMutableDictionary *dat = [NSMutableDictionary dictionary]; NSLog (@"@%", dat); [dat setObject:data forKey:@"nthing"]; [dat writeToFile:path atomically:YES];

Answer 2

为什么是plist文件？ plist很适合数组和字典，但我认为没有理由在plist中存储一个简单的字符串。

怎么样......

NSString *data = ...
NSError *error = nil;
[data writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];

无法创建NSStrings的Plist

2 个答案: