[iOS] performSelector:withObject:afterDelay:调用没有作用的问题及解决方法
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这个问题找了将近一天,baidu、google了很久,竟然没有人遇到同样问题?
performSelector:withObject:afterDelay:和[NSTimer timerWithTimeInterval:invocation:repeats:]都存在此问题:调用后,延迟后(延迟0也一样)没有进入指定的@selecter()中。反复验证发现,这种现象出现在子线程中,主线程中可正常使用。因此必须保证调用performSelector:withObject:afterDelay:是在主线程中。
但没有测试在子线程中再创建个NSTimer用来延迟,应该也可以,反正直接用[NSTimer timerWithTimeInterval:invocation:repeats:]是不行的。
特实现
- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay
方法,保证在主线程中调用成功
// NSObject_performSelectorEx.h
@interface NSObject (performSelectorEx)
- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay;
@end
// NSObject_performSelectorEx.m
#import"NSObject_performSelectorEx.h"
@implementation NSObject (performSelectorEx)
- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay
{
NSMethodSignature *sig = [self methodSignatureForSelector:aSelector];
if (!sig)
{
return;
}
NSInvocation *invo = [NSInvocationinvocationWithMethodSignature:sig];
[invo setTarget:self];
[invo setSelector:aSelector];
[invo setArgument:&anArgument atIndex:2];
[invoretainArguments];
NSMethodSignature *sigMT = [invo methodSignatureForSelector:@selector(performSelector:withObject:afterDelay:)];
NSInvocation *invoMT = [NSInvocationinvocationWithMethodSignature:sigMT];
[invoMT setTarget:invo];
[invoMT setSelector:@selector(performSelector:withObject:afterDelay:)];
SEL arg1 = @selector(invoke);
void *arg2 = nil;
NSTimeInterval arg3 = delay;
[invoMT setArgument:&arg1 atIndex:2];
[invoMT setArgument:&arg2 atIndex:3];
[invoMT setArgument:&arg3 atIndex:4];
[invoMTretainArguments];
[invoMTperformSelectorOnMainThread:@selector(invoke)withObject:nilwaitUntilDone:NO];
}
@end
- [iOS] performSelector:withObject:afterDelay:调用没有作用的问题及解决方法
- [iOS] performSelector:withObject:afterDelay:调用没有作用的问题及解决方法
- [iOS] performSelector:withObject:afterDelay:调用没有作用的问题及解决方法
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