iOS 數據存儲

iOS數據存儲包括以下幾種存儲機制：

屬性列表

對象歸檔

SQLite3

CoreData

AppSettings

普通文件存儲

1、屬性列表

1. //
2. // Persistence1ViewController.h
3. // Persistence1
4. //
5. // Created by liu lavy on 11-10-3.
6. // Copyright 2011 __MyCompanyName__. All rights reserved.
7. //
9. #import <UIKit/UIKit.h>
10. #define kFilename @"data.plist"
12. @interface Persistence1ViewController : UIViewController {
13. UITextField *filed1;
14. UITextField *field2;
15. UITextField *field3;
16. UITextField *field4;
17. }
18. @property (nonatomic, retain) IBOutlet UITextField *field1;
19. @property (nonatomic, retain) IBOutlet UITextField *field2;
20. @property (nonatomic, retain) IBOutlet UITextField *field3;
21. @property (nonatomic, retain) IBOutlet UITextField *field4;
23. - (NSString *)dataFilePath;
24. - (void)applicationWillResignActive:(NSNotification *)notification;
26. @end

1. //
2. // Persistence1ViewController.m
3. // Persistence1
4. //
5. // Created by liu lavy on 11-10-3.
6. // Copyright 2011 __MyCompanyName__. All rights reserved.
7. //
9. #import "Persistence1ViewController.h"
11. @implementation Persistence1ViewController
12. @synthesize field1;
13. @synthesize field2;
14. @synthesize field3;
15. @synthesize field4;
17. //數據文件的完整路徑
18. - (NSString *)dataFilePath {
19. //檢索Documents目錄路徑。第二個參數表示將搜索限制在我們的應用程序沙盒中
20. NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUSErDomainMask, YES);
21. //每個應用程序只有一個Documents目錄
22. NSString *documentsDirectory = [paths objectAtIndex:0];
23. //創建文件名
24. return [documentsDirectory stringByAppendingPathComponent:kFilename];
25. }
27. //應用程序退出時，將數據保存到屬性列表文件
28. - (void)applicationWillResignActive:(NSNotification *)notification {
29. NSMutableArray *array = [[NSMutableArray alloc] init];
30. [array addObject: field1.text];
31. [array addObject: field2.text];
32. [array addObject: field3.text];
33. [array addObject: field4.text];
34. [array writeToFile:[self dataFilePath] atomically:YES];
35. [array release];
36. }
38. /*
39. // The designated initializer. Override to perform setup that is required before the view is loaded.
40. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
41. self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
42. if (self) {
43. // Custom initialization
44. }
45. return self;
46. }
47. */
49. /*
50. // Implement loadView to create a view hierarchy programmatically, without using a nib.
51. - (void)loadView {
52. }
53. */
57. // Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
58. - (void)viewDidLoad {
59. [super viewDidLoad];
60. NSString *filePath = [self dataFilePath];
61. //檢查數據文件是否存在
62. if([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
63. NSArray *array = [[NSArray alloc] initWithContentsOfFile:filePath];
64. field1.text = [array objectAtIndex:0];
65. field2.text = [array objectAtIndex:1];
66. field3.text = [array objectAtIndex:2];
67. field4.text = [array objectAtIndex:3];
68. [array release];
69. }
70. UIApplication *app = [UIApplication sharedApplication];
71. [[NSNotificationCenter defaultCenter] addObserver:self
72. selector:@selector(applicationWillResignActive:)
73. name:UIApplicationWillResignActiveNotification
74. object:app];
75. [super viewDidLoad];
76. }
79. /*
80. // Override to allow orientations other than the default portrait orientation.
81. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
82. // Return YES for supported orientations
83. return (interfaceOrientation == UIInterfaceOrientationPortrait);
84. }
85. */
87. - (void)didReceiveMemoryWarning {
88. // Releases the view if it doesn't have a superview.
89. [super didReceiveMemoryWarning];
91. // Release any cached data, images, etc that aren't in use.
92. }
94. - (void)viewDidUnload {
95. self.field1 = nil;
96. self.field2 = nil;
97. self.field3 = nil;
98. self.field4 = nil;
99. [super viewDidUnload];
100. }
103. - (void)dealloc {
104. [field1 release];
105. [field2 release];
106. [field3 release];
107. [field4 release];
108. [super dealloc];
109. }
111. @end