[__NSCFDictionary setObject：forKey：]：發送到不可變對象的變異方法

Question

-(id)init{ 
    if (self==[super init]) {    
     NSMutableArray *listname = [[NSMutableArray alloc]initWithObjects:@"cu",@"al",@"zn",@"au",@"ru",@"fu",@"rb",@"pb",@"wr", nil];    
     NSMutableArray *listVolumn = [NSMutableArray arrayWithCapacity:[listname count]];   
     for (int i=0; i<[listname count]; i++) { 
      [listVolumn addObject:[NSNumber numberWithLong:0]]; 
     } 
     nsmutabledictionary = [[NSDictionary alloc] initWithObjects:listVolumn forKeys:listname]; 
    } 
    return self; 
} 

在我的init方法中，我定義了兩個NSMutableArray，並將其添加到NSMutableDictionary nsmutabledictionary中。在我的另一種方法 ：

[nsmutabledictionary setObject:[NSNumber numberWithLong:100] forKey:@"cu"]; 

但它墜毀在上述行：

Answer 1

nsmutabledictionary = [[NSDictionary alloc] initWithObjects:listVolumn forKeys:listname]; 

應該

nsmutabledictionary = [[NSMutableDictionary alloc] initWithObjects:listVolumn forKeys:listname]; 

Answer 2

在你的代碼中，我看到nsmutabledictionary = [[NSDictionary alloc] initWithObjects:listVolumn forKeys:listname]; 那行，你聲明它是NSDictionary而你的意圖是NSMutableDictionary