ios计算一段代码执行时间

CFAbsoluteTime startTime =CFAbsoluteTimeGetCurrent();
//在这写入要计算时间的代码
...
CFAbsoluteTime linkTime = (CFAbsoluteTimeGetCurrent() - startTime);
NSLog(@"Linked in %f ms", linkTime *1000.0);
//打印出来为代码执行时间 单位ms

//START:link
- (BOOL)link
{
	CFAbsoluteTime startTime =CFAbsoluteTimeGetCurrent();
	GLintstatus;
	glLinkProgram(program);
	glGetProgramiv(program,GL_LINK_STATUS, &status);
	if(status ==GL_FALSE)
	returnNO;
	if(vertShader){
		glDeleteShader(vertShader);
		vertShader=0;
	}
	if(fragShader){
		glDeleteShader(fragShader);
		fragShader=0;
	}
	CFAbsoluteTime linkTime = (CFAbsoluteTimeGetCurrent() - startTime);
	NSLog(@"Linked in %f ms", linkTime *1000.0);
	returnYES;
}