UIPicker 视图不显示来自 JSON 数组的数据
Posted
技术标签:
【中文标题】UIPicker 视图不显示来自 JSON 数组的数据【英文标题】:UIPicker view not displaying data from JSON array 【发布时间】:2011-09-18 15:48:24 【问题描述】:我有一个 UIPicker 视图,我需要为其加载来自 JSON 提要的数据。 我能够将数组数据写入 NSLOG 并显示它,但无法在 UIPickerview 中看到它。请查看下面的代码并帮助我
请告诉我如何在单击 UI 按钮时显示 UIPicker 视图并在选择值时关闭 UIPickerview。
#import "orderSamples.h"
#import "SBJson.h"
#import "JSON.h"
@implementation orderSamples
NSMutableArray *products;
NSArray *list;
NSMutableData *responseData;
/*
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self)
// Custom initialization
return self;
- (void)didReceiveMemoryWarning
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
*/
- (void)viewDidLoad
[super viewDidLoad];
products = [[NSMutableArray alloc] init];
responseData = [[NSMutableData data] retain];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http JSON URL"]];
[[NSURLConnection alloc] initWithRequest:request delegate:self ];
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
NSLog(@"didReceiveResponse");
[responseData setLength:0];
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
[responseData appendData:data];
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
NSLog(@"Connection failed: %@", [error description]);
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
[connection release];
list = [[NSMutableArray alloc] init];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
//[responseData release];
NSDictionary *dictionary = [responseString JSONValue];
NSArray *response = [[dictionary valueForKey:@"products"] retain];
list = [response valueForKey:@"product_name"];
NSLog(@"Here is the products list: %@",[response valueForKey:@"product_name"]);
self.pickerData = list;
[list release];
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
return 1;
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
return [list count];
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
return [list objectAtIndex:row];
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
NSString *str = [list objectAtIndex:row];
NSLog(@"Selected : %@" , str);
【问题讨论】:
【参考方案1】:我认为问题在于这行代码:
list = [dictionary valueForKey:@"products"];
这是为您的“列表”变量分配一个对象,但该对象将被自动释放。而是尝试:
list = [[dictionary valueForKey:@"products"] retain];
您可能应该使用实例变量而不是全局变量,尽管如果您一次只有一个网络连接,这并不重要。
【讨论】:
当我尝试更改行并打印列表 objectAtIndex:1 时,我能够 NSLog 值。奇怪,但它没有显示在pickerView上 我确实调整了代码并尝试了一些不同的东西,但仍然有效。我已经更新了我的最新代码。谁能帮忙。 发现了问题.. 硬编码数组在 viewdidLoad 方法中有效,但在 connectionDidFinishLoading 方法中无效。 UIPickerview 似乎没有在那里加载。以上是关于UIPicker 视图不显示来自 JSON 数组的数据的主要内容,如果未能解决你的问题,请参考以下文章