Question

我遇到了一个奇怪的问题，我无法使用崩溃我的应用程序的array.count。

@interface LAMasterViewController ()

NSMutableArray * claimReports

@end
    -(void)  ViewDidLoad
    {
       claimReports = [[NSMutableArray alloc] init];
        [claimReports addObjectsFromArray:[[LADataModelController getSingleton] getClaimReportsOrderedByIncidentDate] ];

    }

-(NSArray *) getClaimReportsOrderedByIncidentDate
{ // it returns one record
    NSManagedObjectContext *context = [self managedObjectContext];
    NSError *error;
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [ NSEntityDescription entityForName:@"ClaimReport" inManagedObjectContext:context];
    NSSortDescriptor *sortByIncidentDate = [[NSSortDescriptor alloc] initWithKey:@"dateOfIncident" ascending:NO];
    [request setEntity:entity];
    [request setSortDescriptors: [NSArray arrayWithObject: sortByIncidentDate]];

    NSArray *array = [context executeFetchRequest:request error:&error];
    NSLog(@"Array Count %i" ,array.count);
    return  array;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

  return claimReports.count; //crashes here

}

错误： - [LSClaimReport count]：发送到实例0xa54afc0的无法识别的选择器 2014-04-01 14：56：29.022 LossAdjusting [6956：70b] * 由于未捕获的异常终止应用程序＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39; - [LSClaimReport count] ：无法识别的选择器发送到实例0xa54afc0＆＃39;

我在这里错过了什么。看起来很傻。请指导。感谢

Answer 1

简而言之，您正在将LSClaimReport的实例视为NSMutableArray实例。

结束。

编辑好的，抛开一边，你对实例变量和局部变量感到困惑，并混淆了你的一个实例变量的类型。

在ViewDidLoad中（如果不正确，那么如果它被逐字复制，那么它甚至不会被调用），你引用一个本地版本的claimReports，它被创建然后被丢弃：

-(void)ViewDidLoad
{
    NSMutableArray *claimReports = [[NSMutableArray alloc] init];
    [claimReports addObjectsFromArray:[[LADataModelController getSingleton] getClaimReportsOrderedByIncidentDate] ];
}

稍后您将引用实例变量version：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return claimReports.count; //crashes here
}

这显然是LSClaimReport个实例，而不是NSMutableArray。

所以看起来像：

您在@interface。
您没有正确初始化它（您已修复该位）。

Answer 2

请删除本地Arraydeclaration：

NSMutableArray * claimReports = [[NSMutableArray alloc] init];

改为使用：

claimReports = [[NSMutableArray alloc] init];

如果还没有类变量，请将其添加到@interface-declaration：

@interface LAMasterViewController ()
{
    NSMutableArray * claimReports
}
@end

@implementation LAMasterViewController

Answer 3

将此内容写入您的.h文件

   NSMutableArray * claimReports;

和你的.m

    -(void)viewDidLoad{
              claimReports = [[NSMutableArray alloc] init];
             [claimReports addObjectsFromArray:[[LADataModelController getSingleton] getClaimReportsOrderedByIncidentDate] ];
              }

Answer 4

您的代码几乎没有问题，清理它们有助于解决问题，主要问题'-[LSClaimReport count]: unrecognized selector sent to instance 0xa54afc0'是因为您在count的实例上调用了LSClaimReport不应该发生。您的代码似乎认为claimReports是LSClaimReport的实例，而不是NSMutableArray的实例。

至于您的代码，我建议您更改为（请参阅标记为问题的代码中的注释）

@interface LAMasterViewController ()

// Clearly you want this as a private property so why would you want to change 
// to having this in the .h file which would make it public
// But Issue 1 is here you are missing the semi-colon (`;`) of the end.
@property (nonatomic, strong) NSMutableArray *claimReports;

@end

// Issue two you are missing the `@implementation LAMasterViewController`
@implementation LAMasterViewController

// The synthesize is done automatically so getters/setters/ivar are created automatically

// Issue 3: ViewDidLoad isn't a valid selector so ViewDidLoad will never be called
// It is viewDidLoad
-(void)viewDidLoad
{
    [super viewDidLoad]; // Issue 4: you missed the call to super
    claimReports = [[NSMutableArray alloc] init];
    [claimReports addObjectsFromArray:[[LADataModelController getSingleton] getClaimReportsOrderedByIncidentDate]];

}

-(NSArray *)getClaimReportsOrderedByIncidentDate
{ // it returns one record
    NSManagedObjectContext *context = [self managedObjectContext];
    NSError *error;
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [ NSEntityDescription entityForName:@"ClaimReport" inManagedObjectContext:context];
    NSSortDescriptor *sortByIncidentDate = [[NSSortDescriptor alloc] initWithKey:@"dateOfIncident" ascending:NO];
    [request setEntity:entity];
    [request setSortDescriptors: [NSArray arrayWithObject: sortByIncidentDate]];

    NSArray *array = [context executeFetchRequest:request error:&error];
    NSLog(@"Array Count %i" ,array.count);
    return  array;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

    return claimReports.count;

}

@end

访问NSMutableArray Count ios时应用程序崩溃

4 个答案: