對象是在頭文件中聲明時分配並初始化的,還是需要在我的實現中分配並初始化對象?如果在.h文件中聲明,需要分配和初始化對象
其中哪些是正確的?
.h
@interface myViewController : UIViewController
@property (nonatomic, strong) UIImageView *bgImageView;
@end
.m
- (void)viewDidLoad
{
if (!self.bgImageView) {
NSString *fullpath = [[[NSBundle mainBundle] bundlePath] stringByAppendingString:@"/Background.png"];
self.bgImageView.image = [UIImage imageWithContentsOfFile:fullpath];
[self.view addSubview:self.bgImageView ];
[self.view sendSubviewToBack:self.bgImageView ];
}
或
.h
@interface myViewController : UIViewController
@property (nonatomic, strong) UIImageView *bgImageView;
@end
.m
- (void)viewDidLoad
{
if (!self.bgImageView) {
NSString *fullpath = [[[NSBundle mainBundle] bundlePath] stringByAppendingString:@"/Background.png"];
self.bgImageView = [[UIImageView alloc] initWithImage:[UIImage imageWithContentsOfFile:fullpath]];
[self.view addSubview:self.bgImageView ];
[self.view sendSubviewToBack:self.bgImageView ];
}
第二個是正確的 –
一個快速測試應該顯示選項1不起作用,選項2不起作用... – Wain