不知道为什么我有“EXC Bad Access”错误

Question

我已经使用 Java 和 .Net 编程了一段时间，但从未真正使用过 C 或 Objective C。我仍在尝试理解一些概念。我正在研究一个简单的程序，只是为了看看我如何制作一个结构数组。我相信我是对的。我很难弄清楚如何访问子类并将值存储到我创建的子类中。

我猜我收到错误是因为我使用了 scanf。任何人都可以提供任何帮助吗？

这是我目前所拥有的。

#import <Foundation/Foundation.h>

//Player Prototype: Stores name and wins so far. It can also print out the name and wins
@interface Player : NSObject
{
    NSString *name; //Player name
    NSInteger wins; //Player wins
    NSInteger losses; //Player losses
    NSInteger bp; //extra value for anything I might need in the future.
}

@property (retain, nonatomic) NSString *name;
@property NSInteger wins;
@property NSInteger losses;
@property NSInteger bp;

@end

//Next part

@implementation Player

@synthesize name;
@synthesize wins;
@synthesize losses;
@synthesize bp;

@end

//Brackets

@interface Bracket : NSObject
{
    NSMutableArray *playerarray;
    Player *addplayer;
}

@property (retain, nonatomic) NSMutableArray *playerarray;//array of players
@property (retain, nonatomic) Player *addplayer;//player and data

-(void) SetUp;

@end

//Starting Bracket, working with only 8. Later moving up to 32
@implementation Bracket

@synthesize playerarray;
@synthesize addplayer;

-(void) SetUp;//sets up the array
{
    int i;//counting fun!
    playerarray = [[NSMutableArray alloc] init];//initialize a bracket
    for(i = 0; i < 8; i++)//To add the players
    {

        Player *addplayerx = [Player new];//New instance of Player

        NSString *p;//Not sure if I need two of them.
        NSString *tempname = @"bye";

        NSLog(@"Player %d Name:", i);
        scanf("%s",&p);
        tempname = p;
        NSLog(@"%s", tempname);
        addplayerx.name = p;
        NSLog(@"%s", addplayerx.name);
        addplayerx.wins = 0;
        addplayerx.losses = 0;
        addplayerx.bp = 0;
        [playerarray addObject: addplayerx];
        [addplayerx release];
        [p release];

    }
}


@end



//End function

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    Bracket *starting = [Bracket new];
    [starting SetUp];

    [pool drain];
    return 0;
}

Answer 1

您不能将scanf() 转换为NSString。您需要扫描到一个常规的 C 字符串（确保为它分配内存），然后您可以使用 stringWithUTF8String: 或类似的方式从该字符串构造 NSString。

Answer 2

不要猜测：在调试器下运行应用程序，当它崩溃时，检查回溯。您还可以查看 ~/Library/Logs/DiagnosticReports/foo.crash 中的回溯。

你想做什么，从文件中逐行读取数据？使用text = [NSString stringWithContentsOfFile:path] 然后在所有换行符上拆分text 会容易得多：

NSCharacterSet *newlines = [NSCharacterSet newlineCharacterSet];
NSArray *lines = [text componentsSeparatedByCharactersInSet:newlines];

然后您可以循环并获取玩家姓名：

NSMutableArray *players = [NSMutableArray arrayWithCapacity:[lines count]]; 
NSString *whitespace = [NSCharacterSet whitespaceCharacterSet];
for (NSString *line in lines) {
    NSString *name = [line stringByTrimmingCharactersInSet:whitespace];
    Player *player = [[[Player alloc] init] autorelease];
    player.name = name;
    [players addObject:player];
}