iOS iPhone版本：全尺寸背景图像分辨率

Question

I have a simple, single view app. I have an image which is to be used as the full background. Currently, i have edited the image for both portrait & landscape, in standard (414 X 736) & retina (1242 X 2208).

When i use iOS simulator, the background appears fine in all of the devices (4s > 6 plus). However i'm unsure about if this will hold out when launched/released.

Do i need to provide the image in all different resolutions for each device in my final app?

eg imagePortrait4s.png , imagePortrait5.png , imagePortrait6.png , imagePortrait6plus.png etc

Answer 1

this might help a bit. I can't tell yet...

UIImageView *backgroundImageView = [[UIImageView alloc] initWithImage:_Image];
[backgroundImageView setFrame:[[self view] bounds]];
[[self view] addSubview:backgroundImageView];
//I EXCPECTED THIS NEXT LINE OF CODE TO WORK TO SET A SEPARATE BACKGROUND FOR IPAD...
UIImage *Image = [[UIImage alloc]init];
if ([[UIScreen mainScreen] bounds].size.height == 480) {
    // iPhone, iPod Touch
    Image = [UIImage imageNamed:@"cheetah2.png"];
}
if ([[UIScreen mainScreen] bounds].size.height == 568) {
    // iPhone 5
    Image = [UIImage imageNamed:@"cheetah2.png"];
}
if ([[UIScreen mainScreen] bounds].size.height == 1024) {
    // iPad
    Image = [UIImage imageNamed:@"cheetah2.png"];
}
self.view.backgroundColor = [UIColor colorWithPatternImage:Image];

Answer 2

I have a number of apps in the App Store that only use one image -- the highest resolution one. They scale down fine in practice (on any device). For one background image, you shouldn't see any difference (other than resolution on a non-Retina device).

If you make sure your image is set to "Scale to Fill" it will look good and fill the screen no matter what orientation or device size the user has. (Make sure the important focus of the background is toward the center, because depending on the device, certain edges will be cut off).