Question

我正在尝试阅读plist，内容如下

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
<dict>
    <key>question</key>
    <string>2 + 2 = ?</string>
    <key>A</key>
    <string>2</string>
    <key>B</key>
    <string>4</string>
    <key>C</key>
    <string>3</string>
</dict>
<dict>
    <key>question</key>
    <string>2 + 4 = ?</string>
    <key>A</key>
    <string>3</string>
    <key>B</key>
    <string>6</string>
    <key>C</key>
    <string>9</string>
</dict>
</array>
</plist>

我正在尝试在按下UIButton时更新View Controller，但是从数组中读取时似乎有错误。创建一个错误的数组。第一个问题显示正常但按下按钮时会崩溃。断点显示崩溃的行

self.questionasked.text = question [currentQuestion];

这是代码

- (void)viewDidLoad
{
[super viewDidLoad];
rootArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"question" ofType:@"plist"]];

currentQuestion = -1;
[self showNextQuestion];
}
 -(void) showNextQuestion{
        currentQuestion++;
    int numItems = [rootArray count];
    NSMutableArray *question = [NSMutableArray arrayWithCapacity:numItems];
    NSMutableArray *A = [NSMutableArray arrayWithCapacity:numItems];
    NSMutableArray *B = [NSMutableArray arrayWithCapacity:numItems];
    NSMutableArray *C = [NSMutableArray arrayWithCapacity:numItems]; 

for (NSDictionary *itemData in rootArray) {
    [question addObject:[itemData objectForKey:@"question"]];
    [A addObject:[itemData objectForKey:@"A"]];
    [B addObject:[itemData objectForKey:@"B"]];
    [C addObject:[itemData objectForKey:@"C"]];

    self.questionasked.text = question[currentQuestion];
    self.answer1.text = A[currentQuestion];
    self.answer2.text = B[currentQuestion];
    self.answer3.text = C[currentQuestion];

    }
}

-(IBAction)nextQ:(UIButton *) sender{

[self showNextQuestion];

 }

Answer 1

首先从plist文件获取数据，此处yourArray为NSArray

yourArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"FileName" ofType:@"plist"]];    

for(int i=0; i < yourArray.count; i++)
{
  NSLog(@"%@",[array objectAtIndex:i] objectForKey:@"question"]);
  NSLog(@"%@",[array objectAtIndex:i] objectForKey:@"A"]);
  NSLog(@"%@",[array objectAtIndex:i] objectForKey:@"B"]);
  NSLog(@"%@",[array objectAtIndex:i] objectForKey:@"C"]);
}

Consol中的OutPut显示。

Answer 2

请尝试将这些代码放在for循环之外。

self.questionasked.text = question[currentQuestion];
self.answer1.text = A[currentQuestion];
self.answer2.text = B[currentQuestion];
self.answer3.text = C[currentQuestion];

Answer 3

使用时：

rootArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"question" ofType:@"plist"]];

你会得到autoreleased NSArray，这就是它崩溃的原因，将其更改为：

rootArray = [[NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"question" ofType:@"plist"]] retain];

如果您使用ARC，请使用：

@property (nonatomic, strong) NSArray *rootArray;

和

self.rootArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"question" ofType:@"plist"]];

Answer 4

首先，你需要改变将plist加载到数组中的方式，因为它会自动释放改变它：

rootArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"question" ofType:@"plist"]];

用这个：

 rootArray = [[NSArray alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"question" ofType:@"plist"]];

并且你得到另一个会导致崩溃的错误你必须在showNextQuestion方法中获得这些行：

self.questionasked.text = question[currentQuestion];
    self.answer1.text = A[currentQuestion];
    self.answer2.text = B[currentQuestion];
    self.answer3.text = C[currentQuestion];

在for句子中，代码应该是这样的：

-(void) showNextQuestion{
        currentQuestion++;
    int numItems = [rootArray count];
    NSMutableArray *question = [NSMutableArray arrayWithCapacity:numItems];
    NSMutableArray *A = [NSMutableArray arrayWithCapacity:numItems];
    NSMutableArray *B = [NSMutableArray arrayWithCapacity:numItems];
    NSMutableArray *C = [NSMutableArray arrayWithCapacity:numItems]; 

    for (NSDictionary *itemData in rootArray) {
        [question addObject:[itemData objectForKey:@"question"]];
        [A addObject:[itemData objectForKey:@"A"]];
        [B addObject:[itemData objectForKey:@"B"]];
        [C addObject:[itemData objectForKey:@"C"]];

        }
         self.questionasked.text = question[currentQuestion];
        self.answer1.text = A[currentQuestion];
        self.answer2.text = B[currentQuestion];
        self.answer3.text = C[currentQuestion];


    }

祝你好运..

从plist读取程序时程序崩溃

4 个答案: