如何使用nativeC类型与performSelectorOnMainThread：？ [英] How to use native C types with performSelectorOnMainThread:?

问题描述

我想使用 performSelectorOnMainThread：调用（void）setDoubleValue：（double）value p>

我认为会工作的是：

  NSNumber * progress = numberWithDouble：50.0]; 
 [progressIndicator performSelectorOnMainThread：@selector（setDoubleValue :) 
 withObject：progress 
 waitUntilDone：NO]; 
  

无法使用。

然后我实现了一个辅助方法：

   - （void）updateProgressIndicator：（NSNumber *）progress 
 {
 [progressIndicator setDoubleValue：[progress doubleValue]]; 
} 
  

p>

之后，我尝试使用 NSInvocation 。

  NSInvocation * setDoubleInvocation ;; 
 SEL selector = @selector（setDoubleValue :); 
 NSMethodSignature * signature; 
 signature = [progressIndicator methodSignatureForSelector：selector]; 
 setDoubleInvocation = [NSInvocation invocationWithMethodSignature：signature]; 
 [setDoubleInvocation setSelector：selector]; 
 [setDoubleInvocation setTarget：progressIndicator]; 
 
 double progress = 50.0; 
 [setDoubleInvocation setArgument：& progress atIndex：2]; 
 
 [setDoubleInvocation performSelectorOnMainThread：@selector（invoke）
 withObject：nil 
 waitUntilDone：NO]; 
  

此解决方案适用，但它使用了大量代码，速度相当慢。 （即使我存储调用。）

有其他方法吗？

解决方案

如果你在Snow Leopard，你可以使用Blocks：

  dispatch_async（dispatch_get_main_queue ，^ {
 [progressIndicator setDoubleValue：50.0]; 
}）; 
  

I'd like to call (void)setDoubleValue:(double)value using performSelectorOnMainThread:.

What I thought would work is:

NSNumber *progress = [NSNumber numberWithDouble:50.0];
[progressIndicator performSelectorOnMainThread:@selector(setDoubleValue:)
                                    withObject:progress
                                 waitUntilDone:NO];

Didn't work.

Then I implemented a helper method:

- (void)updateProgressIndicator:(NSNumber *)progress
{
    [progressIndicator setDoubleValue:[progress doubleValue]];
}

Works, but not really clean.

After that I tried it with NSInvocation.

NSInvocation *setDoubleInvocation;;
SEL selector = @selector(setDoubleValue:);
NSMethodSignature *signature;
signature = [progressIndicator methodSignatureForSelector:selector];
setDoubleInvocation = [NSInvocation invocationWithMethodSignature:signature];
[setDoubleInvocation setSelector:selector];
[setDoubleInvocation setTarget:progressIndicator];

double progress = 50.0;
[setDoubleInvocation setArgument:&progress atIndex:2];

[setDoubleInvocation performSelectorOnMainThread:@selector(invoke)
                                      withObject:nil
                                   waitUntilDone:NO];

This solution works, but it uses a lot of code and is quite slow. (Even if I store the invocation.)

Is there any other way?

解决方案

If you are on Snow Leopard, you can use Blocks:

dispatch_async(dispatch_get_main_queue(), ^{
    [progressIndicator setDoubleValue: 50.0];
});

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