Performance Optimization for iOS Apps

Tips & Tricks from personal experience.

Transcript

1. Performance Optimization Vitalii Topoliuk @vtopoliuk
2. - Performance scenarios - How to measure performance - How to improve key scenarios - Tips and Tricks Contents:
3. - Not just about speed - CPU tasks - Memory - Rendering - File I/O - Networking - Power Performance Performance scenarios
4. - Not just about speed - CPU tasks - Memory - Rendering - File I/O - Networking - Power Performance Performance scenarios
5. Overall recommendations Performance scenarios - Don’t guess, just measure - Measure on slowest device - Measure on pessimistic data - Measure on real data
6. How to measure Performance scenarios - Instruments - Logging - Quartz Debug (OS X)
7. CPU Performance Optimization
8. - Unhappy users CPU CPU Tasks Optimization
9. - Unhappy users - System can abort your app CPU CPU Tasks Optimization
10. Time Profiler Demo CPU Tasks Optimization
11. CPU Tasks Optimization
12. CPU Tasks Optimization
13. - do less work - do work later - do slow in background and use placeholders - do work faster Main strategies CPU Tasks Optimization
14. Memory Performance Optimization
15. - Crashes => Unhappy Users Memory Memory Optimization
16. Allocations & Leaks Demo Memory Optimization
17. Memory Optimization
18. Memory Optimization
19. Memory Optimization
20. - do less work - do work later - break down work to smallest batches - use ARC :) - @autoreleasepool Main strategies Memory Optimization
21. .nib loading Tips and Tricks x10 faster
22. ARC vs MMM Tips and Tricks - (void)getPoints:(DPoint[2])outPoint forCenterPoint:(DPoint)centerPoint targetingVector: (DVector)targetingVector skipEquation:(BOOL)skip lineWidth:(DFloat)lineWidth { DVector normVector = DVectorNormalVector(targetingVector); DFloat originX = centerPoint.x + (lineWidth / 2.0f) * normVector.x; ... // some code outPoint[1] = (DPoint){originX, originY}; }
23. ARC vs MMM Tips and Tricks x5 faster on MMM - (void)getPoints:(DPoint[2])outPoint forCenterPoint:(DPoint)centerPoint targetingVector: (DVector)targetingVector skipEquation:(BOOL)skip lineWidth:(DFloat)lineWidth { DVector normVector = DVectorNormalVector(targetingVector); DFloat originX = centerPoint.x + (lineWidth / 2.0f) * normVector.x; ... // some code outPoint[1] = (DPoint){originX, originY}; }
24. Universal solutions Tips and Tricks [self.array addObject:[NSValue valueWithCGPoint:point]] xxx times faster VS @interface DPointsCollection : NSObject - (void)addPoint:(CGPoint)point atIndex:(NSUInteger)index; - (void)removePointAtIndex:(NSUInteger)index; ... @end
25. Sorted NSArray Tips and Tricks [self.array addObject:object]; [self.array sortUsing...];
26. Sorted NSArray Tips and Tricks NSUInteger index = [self.array indexOfObject:object inSortedRange:range options:NSBinarySearchingInsertionIndex usingComparator:comparator]; [self.array insertObject:object atIndex:index];
27. Delay large tasks Tips and Tricks - (void)addPerson:(DPerson*)person { ... [self save]; // large task } - (void)addBook:(DBook*)book { ... [self save]; // large task }
28. Delay large tasks Tips and Tricks - (void)addPerson:(DPerson*)person { ... [self delayedSave]; } - (void)addBook:(DBook*)book { ... [self delayedSave]; } - (void)delayedSave { [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(save) object:nil]; [self performSelector:@selector(save) withObject:nil afterDelay:0.1f]; }
29. API Levels Tips and Tricks - try high level API first - then try lower level NSArray => CFArray => void* NSXMLParser => libxml
30. Questions & Answers Performance Optimization