在SQL中，當二個鍵同時相等時，唯一鍵成立。

ALTER TABLE [dbo].[TABLE] ADD CONSTRAINT
UNIQUE_Table UNIQUE CLUSTERED
(
col1,
col2
)

參考文件

防止繼承的delegate跟原本的衝突(how to extend a protocol for a delegate in objective C)

@interface PlaceView () <MapViewDelegate> {
    id placeSelegate;
}

@end

@implementation PlaceView

- (id)init
{
    self = [super initWithSearch];
    if (self) {
        super.delegate = self;
    }
    return self;
}

# pragma mark public PlaceView

- (void)setDelegate:(id)delegate
{
    placeSelegate = delegate;
}

- (void)done
{
    if ([placeDelegate respondsToSelector:@selector(placeSelected:)])
    {
        [placeDelegate placeSelected:[map placeInfo]];
    }
}

Xcode tip

// TODO:
// FIXME:
// ???
// !!!:
 
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