Using Nsinvocation to abstract the method and realize the lock-up of the method

We need to be in the actual development of a discrete way to lock the thread safety, of course, we have a variety of implementation, this is just one of the more convenient to use.

+ (ID) performselectorwithtarget: ( ID target selector: (SEL) selector withobject: (ID) arg1,... ns_requires_nil_termination ;

{

@synchronized(self) {

ID result =nil;

nsmethodsignature *sig = [targetmethodsignatureforselector: selector];

if (!sig)return result;

nsinvocation* myinvocation = [nsinvocationinvocationwithmethodsi Gnature: sig];

[myinvocation settarget: target];

[myinvocation setselector: selector];

int argumentstart =2;

va_list args;

va_start(args, arg1); //scan for arguments after firstobject.

//Get rest of the objects until nil is found

for (id obj = arg1; obj! =nil; obj = V A_arg(args,ID)) {

[myinvocation setargument: &objatindex: Argumentstart];

argumentstart++;

}

va_end(args);

[myinvocation retainarguments];

[myinvocation invoke];

// Get return value type

constchar *returntype = sig. Methodreturntype ;

// Declare return value variable

// If there is no return value, that is, the message is declared void, then returnvalue=nil

if(! strcmp (ReturnType,@encode(void))) {

result = Nil ;

}

// If the return value is an object, assign a value to the variable

Elseif(! strcmp (ReturnType,@encode(ID))) {

[myinvocation getreturnvalue: &result];

}else{

// If the return value is normal type nsinteger BOOL

// return value length

nsuinteger length = [sigmethodreturnlength];

// request memory by length

void *buffer = (void *)malloc(length);

// Assign a value to a variable

[myinvocation getreturnvalue: buffer];

if(! strcmp (ReturnType,@encode(BOOL))) {

result = [nsnumbernumberwithbool:* ((BOOL ( *) buffer)];

}

Elseif(! strcmp (ReturnType,@encode(nsinteger))) {

result = [nsnumbernumberwithinteger:* (Nsinteg ER*) (buffer)];

}else {

result = [nsvaluevaluewithbytes: Buffer objctype: ReturnType];

}

free(buffer);

}

return result;

}

}

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Using Nsinvocation to abstract the method and realize the lock-up of the method