iOS 根据bundle中的文件名读取图片

转载自：http://www.jishudog.com/18394/html

1. + (UIImage *)imageWithFileName:(NSString *)name {
2. NSString *extension = @"png";
3.  
4. NSArray *components = [name componentsSeparatedByString:@"."];
5. if ([components count] >= 2) {
6. NSUInteger lastIndex = components.count - 1;
7. extension = [components objectAtIndex:lastIndex];
8.  
9. name = [name substringToIndex:(name.length-(extension.length+1))];
10. }
11.  
12. // 如果为Retina屏幕且存在对应图片，则返回Retina图片，否则查找普通图片
13. if ([UIScreen mainScreen].scale == 2.0) {
14. name = [name stringByAppendingString:@"@2x"];
15.  
16. NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:extension];
17. if (path != nil) {
18. return [UIImage imageWithContentsOfFile:path];
19. }
20. }
21.  
22. if ([UIScreen mainScreen].scale == 3.0) {
23. name = [name stringByAppendingString:@"@3x"];
24.  
25. NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:extension];
26. if (path != nil) {
27. return [UIImage imageWithContentsOfFile:path];
28. }
29. }
30.  
31. NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:extension];
32. if (path) {
33. return [UIImage imageWithContentsOfFile:path];
34. }
35.  
36. return nil;
37. }