在iPhone SDK中将对象添加到数组时出现问题

我在iPhone SDK中将对象添加到NSArray时遇到问题。问题是它只添加了我字典的最后一个对象。代码如下：

NSArray * processes = [[UIDevice currentDevice] runningProcesses];
for (NSDictionary * dict in processes){
    runningprocesses = [[NSMutableArray alloc] init];
    NSString *process = [dict objectForKey:@"ProcessName"];
    [runningprocesses addObject:process];
}

---

当我输入NSLog

[dict objectForKey:@“ProcessName”]

时，它会显示所有进程，但如果我尝试添加它们，它只会添加最后一个进程。可能会发生什么情况？

我重新编辑了您的代码，建议您尝试：

NSArray * processes = [[UIDevice currentDevice] runningProcesses];
NSMutableArray *runningprocesses = [[NSMutableArray alloc] initWithCapacity:[processes count]];
for (NSDictionary * dict in processes){
    NSString *process = [dict objectForKey:@"ProcessName"];
    [runningprocesses addObject:process];
}

---

这对我来说很有用：

在代码中，每次循环迭代时，

runningprocesss

数组都指向一个新实例

要修复此问题，请将数组实例化移到for循环之外：

NSArray * processes = [[UIDevice currentDevice] runningProcesses];
NSMutableArray *runningprocesses = [[NSMutableArray alloc] init];
for (NSDictionary * dict in processes){

    NSString *process = [dict objectForKey:@"ProcessName"];
    [runningprocesses addObject:process];
}

---

每次在for循环中都试图分配“runningprocesss”数组。这就是为什么在for循环的末尾只有一个对象。尝试替换此代码

NSArray * processes = [[UIDevice currentDevice] runningProcesses];
runningprocesses = [[NSMutableArray alloc] init];
for (NSDictionary * dict in processes){
    NSString *process = [dict objectForKey:@"ProcessName"];
    [runningprocesses addObject:process];
}

---

这应该是可行的。

您应该将

alloc init

语句移到

for

循环之外。下面是下面的代码

runningprocesses = [[NSMutableArray alloc] init];
NSArray * processes = [[UIDevice currentDevice] runningProcesses];

for (NSDictionary * dict in processes)
{
    NSString *process = [dict objectForKey:@"ProcessName"];
    [runningprocesses addObject:process];
}

---

+1：唯一使用initWithCapacity的答案是：对于NSArray creationies来说，我是一个“容量纳粹”。。。这是我真正信任可变数据的唯一方法，因为在代码中，每次循环迭代时，runningprocesses数组都指向一个新实例。