Fast Enumeration With an NSMutableArray that holds an NSDictionary
Is it possible to use fast enumeration with an NSArray that contains an NSDictionary?
I'm running through some Objective C tutorials, and the following code kicks the console into GDB mode
NSMutableArray *myObjects = [NSMutableArray array];
NSArray *theObjects = [NSArray arrayWithObjects:@"easy as 1",@"easy as two", @"Easy as Three"];
NSArray *theKeys = [NSArray arrayWithObjects:@"A",@"B",@"C"];
NSDictionary *theDict = [NSDictionary dictionaryWithObjects:theObjects forKeys:theKeys];
[myObjects addObject:theDict];
for(id item in myObjects)
{
NSLog(@"Found an Item: %@",item);
}
If I replace the fast enumeration loop with a traditional counting loop
int count = [myObjects count];
for(int i=0;i<count;i++)
{
id item;
item = [myObjects objectAtIndex:i];
NSLog(@"Found an Item: %@",item);
}
The application runs without a crash, and the dictionary is output to the console window.
Is this a limitation of Fast Enumeration, or am I missing some subtly of the language? Are there other gotchas when nesting collections like this?
For bonus points, how could I used GDB to debug this mysel开发者_高级运维f?
Oops! arrayWithObjects:
needs to be nil-terminated. The following code runs just fine:
NSMutableArray *myObjects = [NSMutableArray array];
NSArray *theObjects = [NSArray arrayWithObjects:@"easy as 1",@"easy as two", @"Easy as Three",nil];
NSArray *theKeys = [NSArray arrayWithObjects:@"A",@"B",@"C",nil];
NSDictionary *theDict = [NSDictionary dictionaryWithObjects:theObjects forKeys:theKeys];
[myObjects addObject:theDict];
for(id item in myObjects)
{
NSLog(@"Found an Item: %@",item);
}
I'm not sure why using a traditional loop hid this error.
精彩评论