不兼容的指針類型初始化'CGContextRef *'

Question

不會說謊，我試圖按照一本書中的教程，我無法通過這個警告。

Incompatible pointer types initializing 'CGContextRef *' (aka 'struct CGContext **') with an expression of type 'CGContextRef' (aka 'struct CGContext *')

有問題的行是：CGContextRef *imageContext = UIGraphicsGetCurrentContext();

- (IBAction)hide:(id)sender { 
    CGContextRef *imageContext = UIGraphicsGetCurrentContext(); 
    if (_myIcon.alpha == 1) { 
     [UIView beginAnimations:nil context:imageContext]; 
     [UIView setAnimationCurve:UIViewAnimationCurveEaseOut]; 
     [UIView setAnimationDuration:3]; 
     [UIView setAnimationDelegate:self]; 
     _myIcon.alpha = 0.0; 
     [_hideButton setTitle:@"Show" forState:UIControlStateNormal]; 
    } else if (_myIcon.alpha == 0.0) { 
     [UIView beginAnimations:nil context:imageContext]; 
     [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; 
     [UIView setAnimationDuration:3]; 
     [UIView setAnimationDelegate:self]; 
     _myIcon.alpha = 1; 
     [_hideButton setTitle:@"Hide" forState:UIControlStateNormal]; 
    } 

    [UIView commitAnimations]; 

} 

Answer 1

CGContextRef不是類。你不需要指針。更改此：

CGContextRef *imageContext = UIGraphicsGetCurrentContext(); 

到：

CGContextRef imageContext = UIGraphicsGetCurrentContext(); 

看的文檔爲UIGraphicsGetCurrentContext功能。返回類型是CGContextRef，而不是CGContextRef *。