Question

Is there something wrong with this code? I m trying to set up some buttons by defining at run time the label, the callback selector, and, later, a pointer to the UIButton itself. But with this code, I get EXC_BAD_ACCESS. It gos away if I delete the line with NSSelectorFromString. But since this is just an object being added to the dictionary, I don t understand shy it fails.

NSMutableDictionary *attachButtonDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                        @"Attach To Job",@"keyForLabel",
                                        NSSelectorFromString(@"attachToJob"), @"keyForSelector",
                                        nil];

Answer 1

a 选择人不是排他性物体;选择人代表方法名称不透明。

the program will crash when adding it to the dictionary because it cannot be messaged. for example, it cannot be retained when added.

Answer 2

页: 1 页: 1

仅储存插座和在你建立 but子电话NSSelectorFromString(时。

Best, Christian

Edit:

NSMutableDictionary *attachButtonDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                                @"Attach To Job",@"keyForLabel",
                                                @"attachToJob", @"keyForSelector",
                                                nil];

UIButton *fancyButton = [[UIButton alloc] init];
[fancyButton addTarget:self action:NSSelectorFromString([attachButtonDictionary objectForKey:@"keyForSelector"]) forControlEvents:UIControlEventTouchUpInside];

Answer 3

虽然你可以把一名选择人储存在字典上,但你可以把他装在安全局。

SEL fooSel = @selector(foo);
NSValue *selWrapper = [NSValue valueWithPointer:fooSel];
NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithObject:selWrapper 
                                                               forKey:@"foo"];
SEL myFooSel = [[dict objectForKey:@"foo"] pointerValue];
[obj performSelector:myFooSel];

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