代表不工作

Question

我有這樣的代碼在我的viewController：爲self.graphview.delegate

- (GraphModel *)graphModel 
{ 
    if (!graphModel) { 
     graphModel = [[GraphModel alloc] init]; 
     NSLog(@"graphModel = %@", graphModel); 
    } 
    return graphModel; 
} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    self.graphView.delegate = [self graphModel]; 
    NSLog(@"self.graphview.delegate = %@", self.graphView.delegate); 
    [self updateUI]; 
} 

但NSLog的只是說（空），即使在NSLog的說是GraphModel我成功創建的對象。怎麼會這樣？

這對graphViewDelegate

@class GraphView; 

@protocol GraphViewDelegate 
- (double)yValueForGraphView:(GraphView *)requestor atPosition:(int)i withPrecision:(int)precision; 
- (double)scaleForGraphView:(GraphView *)requestor; 
@end 

@interface GraphView : UIView { 
    id <GraphViewDelegate> delegate; 
} 

@property (assign) id <GraphViewDelegate> delegate; 

@end 

代碼，然後我在graphView.m

Answer 1

最有可能的猜測有@synthesize delegate：graphView是零。在nil對象上調用任何方法都沒有效果，並返回nil，而.delegate實際上是適當地調用getter或setter。我建議你補充：

NSLog(@"self.graphview = %@", self.graphView); 

作爲一個快速驗證。