使用IF語句更改圖像

Question

我在游戲中設置了一個燃料棒，但我試圖使用if語句根據燃料百分比的低點來改變條形圖像。 出於某種原因，圖像不隨百分比變化。 因此，酒吧仍然滿員。 這里發生了什么？

fuelRemaining = 100;
    FuelRemaining.text = [NSString stringWithFormat:@"%i%%", fuelRemaining];
    FuelBar.image = [UIImage imageNamed:@"fuel_bar_100.png"];
    if (fuelRemaining > 90) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_100.png"];
    }
    else if (fuelRemaining > 80 && fuelRemaining <= 90) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_90.png"];
    }
    else if (fuelRemaining > 70 && fuelRemaining <= 80) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_80.png"];
    }
    else if (fuelRemaining > 60 && fuelRemaining <= 70) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_70.png"];
    }
    else if (fuelRemaining > 50 && fuelRemaining <= 60) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_60.png"];
    }
    else if (fuelRemaining > 40 && fuelRemaining <= 50) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_50.png"];
    }
    else if (fuelRemaining > 30 && fuelRemaining <= 40) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_40.png"];
    }
    else if (fuelRemaining > 20 && fuelRemaining <= 30) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_30.png"];
    }
    else if (fuelRemaining > 10 && fuelRemaining <= 20) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_20.png"];
    }
    else if (fuelRemaining > 0 && fuelRemaining <= 10) {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_10.png"];
    }
    else {
        FuelBar.image = [UIImage imageNamed:@"fuel_bar_0.png"];
    }

Answer 1

首先，通過一些基本的數學簡化：

int fuelRounded = 10.0 * floor((fuelRemaining/10.0)+0.5);
NSString *fuelImageString = [NSString stringWithFormat:@"fuel_bar_%d.png", fuelRounded];
FuelBar.image = [UIImage imageNamed:fuelImageString];

（數學可能需要調整，具體取決於您的游戲邏輯和fuelRemaining可能值。）

其次，看起來你在該方法的頂部將fuelRemaining設置為100 。 在fuelRemaining更改為其他內容后，您需要再次設置圖像。

例如：

- (void) updateFuelViews {
    FuelRemaining.text = [NSString stringWithFormat:@"%i%%", fuelRemaining];

    int fuelRounded = 10.0 * floor((fuelRemaining/10.0)+0.5);
    NSString *fuelImageString = [NSString stringWithFormat:@"fuel_bar_%d.png", fuelRounded];
    FuelBar.image = [UIImage imageNamed:fuelImageString];
}

然后調用[self updateFuelViews]; 每次fuelRemaining變化。

您可能想要研究Key-Value Observing ，它可以讓您在fuelRemaining更改時自動更新燃料視圖。 這有點令人頭疼，但如果你有很多東西不斷變化，可以讓它更容易管理。